The seat was re-created in 1950 when the old Down two MP constituency was abolished as part of the final move to single member seats. Originally the seat consisted of most of the northern parts of County Down, with the south included in South Down. In January 1980, the Boundary Commission's original proposals suggested significantly reducing the size of the constituency and renaming it 'Loughside' on the grounds that this would avoid confusion in the event of borough council elections being held on the same day. As a result, in 1983 the seat was radically cut down as part of an expansion of Northern Ireland's constituencies from 12 to 17, although the name remained unaltered. Significant parts of the constituency were transferred to the new Strangford constituency. In boundary changes proposed by a review in 1995, the seat exchanged territory with Strangford, losing the Dundonald area from Castlereagh and gaining a part of Ards.

The seat now contains the entirety of North Down District as well as Donaghadee and Millisle in Ards.

At the time of writing the Boundary Commission has published provisional recommendations for modifying the boundaries of constituencies in Northern Ireland. No changes have been proposed for North Down. This proved acceptable at the public enquiries and the Assistant Commissioner recommended no change to the constituency meaning that the constituency is likely to remain unchanged.

North Down is one of the most overwhelmingly unionist parts of Northern Ireland, with nationalist parties routinely getting no more than 6% of the vote, if that. However it has arguably the most volatile and unpredictable politics of the entire province. Whereas elsewhere there are effectively three fundamental battles fought in elections - between the Ulster Unionist Party and the Democratic Unionist Party to be the leading unionist party, between the Social Democratic and Labour Party and Sinn Fein to be the leading nationalist party, and between unionism and nationalism as a whole, North Down is different. The lack of any substantial nationalist vote renders the last two battles immaterial. Of Northern Ireland's five main parties, only the Ulster Unionist Party and the Alliance Party of Northern Ireland have historically had a significant organisation and support in the constituency, though the Democratic Unionist Party has recently started to gain a foothold where it hitherto was near non-existent.

In addition the constituency has seen many substantial votes for smaller party groupings and individuals. The Ulster Popular Unionist Party, the Conservative Party, the UK Unionist Party and the Northern Ireland Women's Coalition have all polled substantially in the last fifteen years, whilst in local council elections many independent candidates gain sufficient votes to be elected. The area is the heartland of numerous "one-man parties", of which the Ulster Popular Unionist Party and the UK Unionist Party are the best known but far from the only ones. There have been many examples of elected individuals changing party allegiance and often successfully defending their seats for the new party.

The constituency is the most propsperous in Northern Ireland and is widely considered to be the most similar to an English constituency. In part because of this the seat was the heartland of the Equal Citizenship campaign in the late 1980s which argued that political parties in Britain should organise and contest elections in Northern Ireland, in the hope that this would "normalise" the politics of the province. The Conservative Party established itself (having in earlier years been in alliance with the Ulster Unionist Party until a breakdown in relations in the 1970s) and to date has been relatively strongest in North Down though in recent years its vote has declined heavily from the brief surge in the elections held between 1989 and 1992.

Traditionally levels of turnout in elections are very low by Northern Ireland standards, possibly because the lack of a serious threat of a nationalist victory removes the impetus to vote common among unionists elsewhere in the province. The one significant exception to the levels of turnout was the 1998 referendum on the Good Friday Agreement where turnout reached 80%, a total not come close to since 1921.

The parliamentary constituency was original held by the Ulster Unionist Party with no serious opposition. In 1970 James Kilfedder was first elected and he proceeded to accumulate a high level of personal popularity in the constituency. In 1977 he left the Ulster Unionists in protest over their increasing support for Enoch Powell's proposed policy of integration for Northern Ireland, rather than the restoration of devolved government. Standing as an independent Unionist, Kilfedder successfully defended his seat against a UUP challenge in the 1979 general election. The following year he formed the Ulster Popular Unionist Party, with a few local councillors being successfully elected on the label.

Kilfedder continued to hold his seat. Then in the 1987 general election he agreed an electoral pact with the Ulster Unionists and the Democratic Unionist Party to form a united opposition to the Anglo-Irish Agreement. However the local UUP candidate, Robert McCartney, was opposed to this pact and refused to withdraw. He was expelled from the UUP and so stood as a "Real Unionist" on a platform of complete integration for the province. Kilfedder retained the seat but with a reduced majority. As part of his platform for integration, McCartney had called for the major UK parties to organise and stand in the province and his result gave impetus to this campaign.

The Conservative Party did very well in the 1989 local elections for North Down Borough Council when they became the largest party. They stood candidates in several Northern Ireland constituencies in the 1992 general election, but their strongest prospect was expected to be North Down. Kilfedder by this stage was taking the Conservative whip at Westminster and so was aggrieved by this (and subsequently given a knighthood). In the event the result was similar to 1987, with the Conservatives getting a similar vote to McCartney.

Kilfedder died in 1995 and his loose Ulster Popular Unionist Party faded away even before the resulting by-election. By this time the Northern Ireland Conservatives had collapsed heavily and so there was much speculation about how the by-election would go. The Ulster Unionist Party were hopeful that they could retake the seat, but McCartney also stood, this time as a "UK Unionist" with the support of the Democratic Unionist Party. No candidate stood for the Popular Unionists or any nationalist party. There was a poor turnout in which McCartney won, with the Conservative vote collapsing from 32% to a humiliating 2.1%.

McCartney further established his UK Unionist Party and sought to challenge the existing unionist parties by offering a less sectarian alternative. He held his seat in the 1997 and was also elected to both the Northern Ireland Peace Forum in 1996 and the Northern Ireland Assembly in 1998, though on each occasion he was the only UK Unionist elected from North Down. In the 1998 election the Ulster Unionists had their strongest result in the province and there was much speculation that they could unseat McCartney at the next general election.

A rather public row erupted over the selection of the UUP's candidate. Initially the local assembly member Peter Weir was selected, but his opposition to the Good Friday Agreement and David Trimble's leadership became very prominent and a running source of embaressment to the party. Then Weir was deselected and the new candidate selected, Sylvia Hermon, was supportive of both Trimble and the Agreement. In the 2001 general election campaign the local branch of the Alliance Party of Northern Ireland decided to withdraw their candidate when they felt that it would achieve their objectives better to support Hermon, who defeated McCartney overwhelmingly.

Weir remained as an Assembly member but subsequently defected to the Democratic Unionist Party. In the 2003 Assembly election Weir successfully defended his seat for the DUP, who also gained another MLA from the Northern Ireland Women's Coalition. In the 2005 general election the party battle was altered somewhat by the DUP running Weir, the Alliance putting up a candidate and McCartney, after some speculation, deciding not to stand but to instead endorse Weir. In a strong contest Hermon retained the seat, to become the only Ulster Unionist MP at the moment.

The Annals Of Ulster tell us that the monastery of Bangor was founded by St Comgall in 555 or 559. It was situated roughly where Bangor Abbey Church of ireland currently stands at the head of the town. The monastery became a centre of great learning among the most eminent of Ireland's missionary institutions, although it also suffered greatly at the hands of Viking raiders in the eighth and ninth centuries.

The name 'Bangor' is derived from the Irish Beannchar. The meaning of this word is uncertain but may be related to beann, which means a horn, rocks or a peaked hill, and could refer to Bangor's rocky coastline.

The modern town has its roots in the early seventeenth century when the Scot, Sir James Hamilton, arrived in Bangor, having been granted lands in north Down by King James VI and I in 1605. Tower House, which is now home to the Tourist Information Centre, dates from this time and is a visible reminder of the new order introduced by Hamilton and his Scots settlers.

The town was also an important source of customs revenue for the crown. In the 1780's, Colonel Robert Ward improved the harbour and promoted the cotton industries, which led to increased prosperity in the town. The coming of the railways in 1865 brought further growth and Bangor soon became a fashionable resort for Victorian holidaymakers, as well as a desirable home to the wealthy. Many of the beautiful houses overlooking Bangor Bay date from this period.

Sea bathing and marine sports became popular and visitors from other parts of the United Kingdom increased throughout the Edwardian period. The inter-war period of the early twentieth century saw the development of the fondly remembered Tonic Cinema, Pickie Pool and Caproni's - all three probably the foremost of their type in Ireland.

With the advent of foreign holidays and cheap travel from the 1960's, Bangor declined as a tourist resort and was forced to rethink its future. The second half of the twentieth century saw its role as a dormitory town for Belfast become more important. Its population increased dramatically from around 14,000 in 1930, it had reached 40,000 by 1971 and 58,000 by the end of the century, making it one of the ten largest settlements in all of Ireland. The town expanded most rapidly in the 1980's to accommodate its new residents, absorbing much surrounding countryside. This period also saw the construction of the Ring Road, the marina and the major industrial and retail developments.

Modern day Bangor, with its world-class marina, is a vibrant and fashionable town that benefits from its proximity to Belfast, a modern tranportation network, a buzzing social scene and a plethors of exciting maritime activities.

Groomsport, two miles east of Bangor on the south shore of Belfast Lough, derives its name from the irish Port an Gholla Ghruama which means 'the port of the gloomy servant'. By the seventeenth century it was known as 'Gilgroomsport' and at this time, before Donaghadee became the main port for embarkation for Scotland, Groomsport's harbour was significant enough to have its own Customs House. Indeed, Groomsport narrowily missed out on New World fame when the ship Eagle Wing set out from the port to attempt an early trip to North America in 1636 only to be defeated by bad weather.

By the mid 1800's, Groomsport had a relatively large fishing fleet and housed a lifeboat station in its sheltered bay. The population of the village was employed mainly in agriculture, fishing and loom weaving. Whilst living conditions were hard, the coming of the railway from Holywood to Bangor in 1865 made the village much more accessible and the standard of living improved. Groomsport had its own stop on the Newtownards to Donaghadee line and the village became a popular destination for visitors.

The population was only 360 in the 1951 census but this increased substantially in the last few years with the construction of new housing developments and now exceeds 1000. The harbour had found new popularity, with a sailing cluab and a collection of pleasure craft. Two former fishermen's cottages by the harbour have been restored as an attraction for visitors.

The irish name for Holywood is Ard Mhic Nasca, 'the height of the son of Nasca', but the 'holy wood' from which the town takes its modern name was beside the early Christian church on the site of the present ruins of the medieval Old Priory. It appears first in latinised form as Sanctus Boscus and the earliest written use of the anglicized version occurs on a document from the fourteenth century and is written 'Haliwoode'.

In the early nineteenth century Holywood, like many other costal villages throughtout Ireland, became popular as a resort for sea bathing. Many wealty Belfast merchants chose the town and its surrounding area to build their large homes, including the Kennedy's of Cultra and the Harrison's of Holywood. Dalchoolin house stood on the site of the present Transport Museum, while Cultra Manor was built in 1902 - 1904 and now houses part of the Ulster Folk Museum.

The railway line from Belfast to Holywood opened in 1848 and this led to further prosperity. The population of Holywood was approximately 3500 in 1900 but this figure had grown to 12,000 by 2001. This growth, coupled with the growth of Bangor, led to the construction of the Holywood bypass in the early 1970's. Holywood today is a popular residential area and is well known for its fashionable shops, boutiques, arts and crafts.

The Priory graveyard is the resting place for many distinguished citizens including the Praeger family: Robert Lloyd Praeger (1865-1953) was an internationally renowned botanist and his sister Rosamund (1867-1954) gained fame as a sculptor.

Holywood also houses Ireland's only Maypole, around which local children dance every May Day. Its origin is uncertain, but local folklore claims that it dates from 1700 when a Dutch ship is said to have run aground on the shore nearby, and the crew erected the broken mast as a show of appreciation for the assistance offered by the townfolks!