The constituency is considered a safe seat of the Conservative Party although the seat has been won by the Labour Party in three general elections – in addition to the 1991 by-election. The current MP is the Conservative David Davies, elected in 2005 and a former member for the Welsh Assembly seat of the same name. To avoid confusion with the Yorkshire Conservative David Davis, he is named in Hansard as "David T.C. Davies".
As first used in the 1918 general election, the constituency was a creation of the Representation of the People Act 1918 as one of six constituencies covering the county of Monmouth. Prior to the 1918 election the county had been covered, nominally, by the county constituencies of Northern Monmouthshire, Southern Monmouthshire, and Western Monmouthshire, and the Monmouth Boroughsborough constituency. By 1918, however, administrative county boundaries were out of alignment with constituency boundaries. The new constituency boundaries took account of the new local government boundaries. The other Monmouthshire constituencies defined by the 1918 legislation were the county constituencies of Abertillery, Bedwellty, Ebbw Vale and Pontypool, and the borough constituency of Newport. This general pattern was maintained until 1983, nine years after the administrative county they were based on had been abolished, but there were some boundary changes during the 1918 to 1983 period. In 1918 the Monmouth constituency was defined as consisting of the municipal boroughs of Abergavenny, and Monmouth, the urban districts of Caerleon, Chepstow, and Usk, the rural districts of Abergavenny, Chepstow, Magor, Monmouth, Cwmbran and Pontypool, and part of the rural district of St Mellons. The same boundaries were used for the general elections of 1922, 1923, 1924, 1929, 1931, 1935 and 1945. New boundaries, created by the House of Commons Act 1949, were used for the 1950 general election, and the Monmouth constituency was defined as consisting of the municipal boroughs of Abergavenny and Monmouth, the urban districts of Caerleon, Chepstow, Cwmbran and Usk, and the rural districts of Abergavenny, Chepstow, Magor and St Mellons, Monmouth, and Pontypool. For the 1951 general election, there was some alteration to the boundaries of rural district of Magor and St Mellons. The constituency was redefined again for the 1955 general election, taking account of new local government boundaries. The result was the same list of boroughs and districts as for the 1951 election. 1951 boundaries were used also in the general elections of 1959, 1964, 1966, 1970, February 1974, October 1974 and 1979. In 1974, under the Local Government Act 1972, the local government county of Monmouth was abolished. For the 1983 general election, new constituency boundaries were drawn, taking account of new local government boundaries.
Members of Parliament
The following list does not include MPs who actually represented Monmouth Boroughs:
