David Cameron and Brendan Barber: On Europe even we can agree – for British workers it’s better in

We oppose each other on many things, but we both know the poorest in our country would be badly hit by a Brexit

A former trade union leader and a Conservative prime minister have never before put pen to paper together. We do so today in very special circumstances. With the prospects for working people all across Britain at stake on 23 June, it is right that the rules of conventional politics be temporarily set aside. There are, of course, many things on which the two of us disagree. But we are united in our conviction that Britain, and Britain's workers, will be better off in a reformed Europe than out on our own.

While staying in Europe offers workers in the UK the best prospects of rising prosperity, leaving poses what we call a triple threat: to working people's jobs, to their wages and to the prices we all pay in the shops. Let us take each in turn.

Related: Brexit could cost 100bn and nearly 1m jobs, CBI warns

Related: George Osborne: Brexit would leave UK 'permanently poorer'