They have not been affiliated to the Labour Party since the High Blair Period. But both the National Union of Rail, Maritime and Transport Workers, and the Fire Brigades Union, are affiliated to the Labour Representation Committee. That is constitutionally committed to the election of a Labour Government.
I do not know about the FBU, but every April a ritual is performed between Labour and the RMT. The union sends in its affiliation fee, and the Party Treasurer sends back the cheque uncashed. Yet the High Blair Period was a long time ago.
Or was it? Labour is perfectly happy to take Blair's blood-soaked Kazakh money, and prefers it to the small voluntary donations that their trade unions collect from millions of ordinary working people in the United Kingdom.
The RMT is clearly collecting what would be its affiliation dues. Perhaps the FBU is also doing so. Together, they ought to say that they would match any donation that Blair sought to make to Labour, provided that the party rejected his offer in favour of theirs.
That could take some doing. But they might be surprised at how much appeal among the public a public appeal might have.