Solidarity is a United Kingdom trade union formed in late 2005 by the far-right British National Party (BNP).

The first union president was Adam Walker, a BNP member and three times a parliamentary candidate (in Bishop Auckland in 2010 and 2017 and in Rotherham in 2015).

In a 2006 report in the newspaper Wales on Sunday, John Walker, then national treasurer of the BNP, claimed that the union was likely to contribute funds to the party: "There probably will be a political levy at some stage to the BNP just as other unions raise money for Labour.

It is quite possible and feasible that when Solidarity becomes fully functional some element of funds raised will be donated to the BNP, but that will have to be decided through consultation with the membership.

[5] Solidarity's annual returns to the Certification Office from 2006 to 2018 indicate that the union has not established a political fund.