Sir Thomas Arthur Bramsdon was a British solicitor from Portsmouth and a Liberal Party politician who was elected for four non-consecutive terms as a Member of Parliament (MP) for Portsmouth constituencies.

Portsmouth was a borough constituency based upon the borough of Portsmouth in Hampshire. It returned two members of parliament (MPs) to the Parliaments of England, Great Britain and from 1801 the House of Commons of the Parliament of the United Kingdom, elected by the bloc vote system.