WALES and Northern Ireland cannot afford to be left behind by the talks on giving more powers to Scotland, Paul Murphy, a former Secretary of State for both countries, has warned.

The Labour backbencher's caution came as a report by the think-tank, the Royal Society for the encouragement of Arts, Manufacturers and Commerce City Growth Commission, calls for devolution to England's cities, so-called "devo-met".

It argues that allowing the cities to set their own tax, immigration and planning policies alongside devo-max for Scotland could boost UK productivity by £79bn a year - worth approximately five per cent of GDP - by 2030.

In Edinburgh this morning, all five main Scottish parties will meet as part of the Smith Commission process to begin attempts at consensus on which extra powers should be transferred from London to Edinburgh in the wake of the independence referendum result.

As they prepared to do so, Lord ­McConnell, the former Labour First Minister, warned that a cosy back-room deal would not do, stressing: "This has to be seen as based on principle and stand the test of time."

Mr Murphy insisted it was essential that the administrations in Cardiff and Belfast received fair funding in the wake of any new financial settlement for Scotland.

"It is very important for the other two devolved administrations to talk about what happens in Scotland because we cannot get left behind," declared Mr Murphy.

He said the most pressing issue was finance, in particular the Barnett Formula given that Scotland was likely to receive significant tax powers as well as a commitment that its Barnett funding would not be reduced.