Abingdon's voters seem always to have maintained their independence, and the constituency never came under the influence of a "patron" who assumed the right to choose the MP. Nevertheless, this did not always guarantee a pure election, and Porritt records that Abingdon offers the earliest case he was able to trace of a candidate trying to bribe voters with the promise of official office, later one of the most widespread abuses in English elections. In 1698, the defeated candidate, William Hucks, petitioned against the election of Sir Simon Harcourt, but during the hearing of the case it emerged that Hucks had promised that should he be elected an MP he would be made a Commissioner of the Excise, in which case he would use that power to appoint several of the voters to well-paid excise posts. The petition was dismissed and Hucks was committed to the custody of the sergeant-at-arms. (But ten years later, defeated again by Harcourt at the election of 1708, Hucks petitioned once more, on grounds of intimidation and other illegal practices, and this time Harcourt was ejected from his seat and Hucks declared to have been duly elected. Harcourt complained that the decision was a partisan one – which would have been by no means unusual at the period – "insisting to the last that he was the legal member, by a clear majority, by the most fair estimation".)
In 1831, the population of the borough was approximately 5,300, and contained 1,192 houses. This was sufficient for Abingdon to retain its MP under the Great Reform Act. (Indeed, it would have been big enough to retain two MPs had it had them, but there was no question of its representation being increased.) Its boundaries were unaltered, and under the reformed franchise 300 of the residents were qualified to vote.
In 1885 the borough constituency was abolished and the town was moved into a new county, The Northern or Abingdon Division of Berkshire. This constituency consisted of the northern part of the historic county, and as well as Abingdon included the towns of Wantage and Wallingford; it was predominantly agricultural at first, although its character changed during the 20th century with the growth of light industry round Abingdon, and it was generally a safe Conservative seat. This constituency survived essentially intact, with only minor boundary changes, until the 1983 general election, by which time it was simply called Abingdon County Constituency.
Changes in administrative boundaries during the 1970s moved most of the northern part of the historic county of Berkshire, including Abingdon, into the county of Oxfordshire. These changes were reflected in the constituency boundary changes introduced in 1983, and the Abingdon constituency was divided; most of its electors were placed in the new Wantage constituency and a significant minority including electors in the town of Abingdon were placed in the Oxford West and Abingdon constituency. A small part to the south of the constituency had been retained within Berkshire and this area was transferred to Newbury.
The constituency's boundaries were adjusted slightly by the Representation of the People Act 1918, gaining a small part of the Newbury Division. It was redefined in terms of the administrative county of Berkshire and the county districts created by the Local Government Acts of 1888 and 1894 as follows:
The rural districts of Abingdon (the civil parishes of Abingdon St Helen Without, Appleford, Appleton-with-Eaton, Besselsleigh, Cumnor, Draycot Moor, Drayton, Frilford, Fyfield, Garford, Kingston Bagpuize, Lyford, Marcham, Milton, North Hinksey, Radley, South Hinksey, Steventon, Sunningwell, Sutton Courtenay, Sutton Wick, Tubney, Wootton, and Wytham), Wallingford (the civil parishes of Aston Tirrold, Aston Upthorpe, Brightwell-cum-Sotwell, Cholsey, Didcot, East Hagbourne, Little Wittenham, Long Wittenham, Moulsford, North Moreton, South Moreton, and West Hagbourne), and Wantage (the civil parishes of Aldworth, Ardington, Beedon, Blewbury, Brightwalton, Catmore, Chaddleworth, Childrey, Chilton, Compton, Denchworth, East Challow, East Hanney, East Hendred, East Ilsley, Farnborough, Fawley, Goosey, Grove, Hampstead Norris, Harwell, Hermitage, Letcombe Bassett, Letcombe Regis, Lockinge, Peasemore, Sparshlt, Upton, West Challow, West Hanney and West Hendred, and West Ilsley);
The part of the rural district of Faringdon which is within the administrative county of Berks (the civil parishes of Ashbury, Baulking, Bourton, Buckland, Buscot, Charney Bassett, Coleshill, Compton Beauchamp, Eaton Hastings, Fernham, Great Coxwell, Great Faringdon, Hatford, Hinton Waldrist, Kingston Lisle, Little Coxwell, Littleworth, Longcot, Longworth, Pusey, Shellingford, Stanford in the Vale, Uffington, Watchfield, and Woolstone);
The municipal boroughs of Abingdon and Wallingford;
The Representation of the People Act 1948 reorganised parliamentary constituencies, and Abingdon County Constituency was altered marginally, with the part of the rural district of Bradfield being transferred to the County Constituency of Newbury. The official definition of the constituency was:
The boroughs of Abingdon and Wallingford;
the urban district of Wantage;
the rural districts of Abingdon, Faringdon, Wallingford and Wantage.
The constituency was not altered by the Parliamentary Constituencies (England) Orders of 1970, and continued virtually unchanged until it was abolished in 1983.
^Medlycott's election was declared void on petition, and a new election was held
^Southby was returned as elected by the Mayor, but on petition the Commons decided that Stonhouse and not Southby had received the most votes, and eventually declared Stonhouse duly elected
^Harcourt was initially declared elected, but on petition alleging "that Sir Simon, by menaces and by other illegal practices of himself and his agents, procured several votes for him, and several were admitted to vote for him who had no right", the result was overturned and Hucks declared to have been duly elected
^At the election of 1768, Morton was declared re-elected, but on petition the result was overturned and his opponent Bayly declared elected instead
^On petition, Mayor's election was declared void, since as High Sheriff of Berkshire he was not eligible to be elected MP for a borough within the county. A new election was ordered, by which time Mayor had completed his term as sheriff and was re-elected.