The British Brothers' League (BBL) was a British anti-immigration, extraparliamentary,^[1] pressure group,^[2] the "largest and best organised" of its time.^[3] Described as proto-fascist,^[4] the group attempted to organise along paramilitary lines.^[5]

The group was formed in May 1901^[6] in east London as a response to waves of immigration that had begun in 1880 and had seen a rapid increase in the numbers of Russian and Polish Jews, as well as others from Eastern Europe, into the area.^[7] As a result, Captain William Stanley Shaw formed the BBL to campaign for restricted immigration with the slogan 'England for the English' and soon formed a close alliance with local Conservative MP Major Evans-Gordon.^[8] Initially the League was not antisemitic and was more interested in keeping out the poorest immigrants regardless of background, although eventually Jews became the main focus.^[9] The organisation promoted their cause with large meetings, which were stewarded by guards whose role was to eject opponents who entered and raised objections.^[10]

The League claimed 45,000 members, although membership was actually fairly irregular as no subscriptions were lifted and anyone who signed the organisation's manifesto was considered a member, with Tory MP Howard Vincent amongst those to do so. As a result of this, attempts to militarise the group were largely a failure, although the movement continued to organise demonstrations against immigrants.^[9] The Aliens Act 1905, which restricted immigration, was largely seen as a success for the BBL and, as a result, the movement by and large disappeared.^[8]

It officially carried on until 1923, albeit on a tiny scale, and was associated with G. K. Chesterton and the distributist movement.^[11] Nonetheless, they would resurface from time to time as new immigrant scares and shortly before the outbreak of the First World War they were even given a public donation of ten shillings by Arthur Conan Doyle, who had been caught up in a growing public swell of Germanophobia as war loomed.^[12]

The League also left behind a legacy of support for far-right groups in east London and this was exploited by the British Union of Fascists, the British League of Ex-Servicemen and Women, the Union Movement and the National Front who gained followings in the same environs.^[13]