Baptised at Hackney, London, Forster was the eldest son of Matthew Forster, who represented Berwick-upon-Tweed as a Liberal, 1841-53, and, through the merchant house of Forster and Smith, became a major figure in the opening up of British trade in the Gambia. His father had also inherited the family’s interests in the south Durham coal industry, and was a partner in the South Hetton Colliery, county Durham.
Upon his father’s return at the 1852 general election being declared void on petition, 23 Apr. 1853, a meeting of Liberal electors at Berwick-upon-Tweed unanimously passed a motion to invite Forster junior to contest the ensuing by-election in May 1853, where, after a fractious contest, he was returned in second place.
Although his presence in the Commons was sporadic in the 1854 session, Forster became a regular attender thereafter, and followed Palmerston into the division lobby on all major foreign policy issues, voting against Roebuck’s censure of the cabinet, 19 July 1855, and Cobden’s censure motion on Canton, 3 Mar. 1857. His support, however, for church rate abolition, 16 May 1855, for the ballot, 22 May 1855, and for the equalisation of the borough and county franchises, 19 Feb. 1857, saw him dividing against the premier.
Forster confined his handful of known contributions in the Commons to local issues. His father a shareholder in the Hartlepool docks, he pressed the House to reject the Hartlepool pier and port bill, arguing that the proposal to levy duties on ships using the harbour for trade, in order to fund the construction of a harbour of refuge, would only ensure that the ‘persons who did not derive any benefit from the scheme were to pay the expenses’, 20 Mar. 1855. He spoke in favour of Thomas Headlam’s Scottish marriages bill, which was designed to prevent residents of the northern counties of England eloping to Scotland, where marriage could be granted simply by a declaration of consent in the presence of witnesses, 9 May 1855. A resident of Hampstead, he also urged Parliament to reject a clause in the leases and sales of settled estates bill that had been inserted specifically to allow Sir Thomas Wilson, the lord of the manor, to enclose the Heath, a project that Forster felt was designed ‘for no other object ... than to annoy its inhabitants’, 9 Aug. 1855.
At the 1857 general election Forster retired from the representation of Berwick-upon-Tweed to allow his father to attempt to regain his seat, only for the latter to finish bottom of the poll. Neither contested the borough again.
