The tribalism of British politics, which he sensibly deplores, is an inevitable consequence of majority rule in a political structure with few checks or balances on the executive. No amount of co-operation rhetoric will end it.
The litmus test of co-operation would be for Labour to modify its policies to seek a consensus with the Liberal Democrats. Their determination to stick with closed lists of candidates for the European elections eloquently demonstrates that the Joint Consultative Committee is a fraud.
Administrations with absolute majorities destroy debate and consensus. If they are swayed by argument they are accused of a U-turn, when they should be congratulated for using their minds. So decisions are taken in back rooms and stuck to even when mature reflection makes it obvious that they are wrong. Since the outcome of every "debate" is known before it starts, Parliament de-generates into the mud-slinging farce that we see every day.
When I led a Liberal Democrat group on a "hung" council the Labour leader would ask me privately what I thought my group would agree to before he met his own. He would then tell his more extreme colleagues that he agreed with them but those bloody Liberals wouldn't go along with it.
He would tell the rest that I had reluctantly agreed to try and persuade my group to support them.
We then had a genuine debate without a back room in sight and with U- turns galore. We actually tasted democracy.