Opponents of devolution should "grow up", the Welsh secretary has said.

Writing in the Western Mail newspaper Peter Hain argued the way the Scottish parliament and the assemblies in Wales, Northern Ireland and London worked proved that the prime minister was not the "control freak" his critics claim him to be.

"Government in Britain is now underpinned by a policy laboratory. We can all learn from each other," he wrote on Tuesday.

"Not only has the government of Britain become a giant policy laboratory, unnoticed by the Westminster bubble, but there has been a silent revolution, also unnoticed, in which political culture under Labour has become far more pluralistic.

"Far from Tony Blair being a 'control freak', that caricature is confounded by his continuing devolution of power."

"Britain's political culture and our media still has to grow up and realise that devolution means not all differences are splits and not all policy divergences and clashes."

Hain argued for reform of the PR top-up list system, through which 20 assembly members are elected to the Welsh Assembly, some of whom had previously been defeated through the first past the post system.

"In the Clwyd West constituency, for example, three of the four defeated candidates were subsequently elected on the regional list, including one who polled only 7.9 per cent of the vote," he said.

"So winners, despite losing, are then able to call themselves the member for the same constituency."

Instead, the Welsh secretary argued that candidates should choose either to stand for PR list seats or those elected through first past the post.