- Lord AberconwayConservativeMember of the House of LordsPeer since 1953
- The Duke of AbercornConservativeMember of the House of LordsPeer since 1979
- Lord AberdareCrossbenchMember of the House of LordsPeer since 2009
- Lord AberdareConservativeMember of the House of LordsPeer since 1957
- Marquess of Aberdeen and TemairCrossbenchMember of the House of LordsPeer since 1984
- Marquess of AbergavennyCrossbenchMember of the House of LordsPeer since 1954
- Lord AbingerConservativeMember of the House of LordsPeer since 1943
- Leo AbseLabourMP for TorfaenMP since 1958
- Lord AcknerCrossbenchMember of the House of LordsPeer since 1986
- Lord ActonLabourMember of the House of LordsPeer since 2000
- Allen AdamsLabourMP for Paisley NorthMP since 1979
- Mr Gerry AdamsSinn FéinMP for Belfast WestMP since 1997
- Nigel AdamsConservativeMP for Selby and AinstyMP since 2010
- Viscount AddisonConservativeMember of the House of LordsPeer since 1992
- Robert AdleyConservativeMP for ChristchurchMP since 1970
- Lord AdrianCrossbenchMember of the House of LordsPeer since 1977
- Bim AfolamiConservativeMP for Hitchin and HarpendenMP since 2017
- Adam AfriyieConservativeMP for WindsorMP since 2005
- Baroness AfsharCrossbenchMember of the House of LordsPeer since 2007
- Imran Ahmad KhanIndependentMP for WakefieldMP since 2019
- Lord AhmedNon-affiliatedMember of the House of LordsPeer since 1998
- Ms Tasmina Ahmed-SheikhScottish National PartyMP for Ochil and South PerthshireMP since 2015
- Nickie AikenConservativeMP for Cities of London and WestminsterMP since 2019
- The Marquess of AilesburyCrossbenchMember of the House of LordsPeer since 1974
- The Marquess of AilsaConservativeMember of the House of LordsPeer since 1994
- Lord AilwynConservativeMember of the House of LordsPeer since 1976
- Nick AingerLabourMP for Carmarthen West and South PembrokeshireMP since 1992
- Mr Bob AinsworthLabourMP for Coventry North EastMP since 1992
- Mr Peter AinsworthConservativeMP for East SurreyMP since 1992
- Lord AiredaleLiberal DemocratMember of the House of LordsPeer since 1958
- Baroness Airey of AbingdonConservativeMember of the House of LordsPeer since 1979
- The Earl of AirlieCrossbenchMember of the House of LordsPeer since 1968
Source: parliament.uk · 1,424 currently sitting · Open Government Licence v3.0