THE SNP’s Westminster leader yesterday took up the challenge set by David Cameron at Prime Minister’s Questions and sent him a list of problems with Tory devolution plans.

Angus Robertson wrote to Cameron with details of where the Scotland Bill falls short of delivering on the cross-party Smith Commission on more powers.

Robertson also presented Cameron with a recent report from Holyrood’s devolution committee, which includes Tory MSP Alex Johnstone, which made similar complaints.

“The Prime Minister asked for a list, well this is one that even his own party has signed up to,” said Robertson, adding the Bill fell short on Universal Credit, benefits in devolved areas, top-up benefits, carers’ benefits, employment support and the Sewel convention.

The move followed a clash on Wednesday, when Cameron said he had “delivered on all the promises" made in the Vow, and suggested the SNP was obsessed by process because it was afraid to discuss practical policies.

“You give me a list of the things that were promised and were not delivered, and then we can have a very reasonable conversation. Until then, it is all bluster from the SNP,” the PM said.

Although Robertson’s list refers to complex legislation arising from the Smith Commission, rather than the limited, broad brush elements of the Vow, he said: “On welfare, employment and the constitution, the Bill does not deliver on what was promised in the Vow or what the people of Scotland voted for in May.

“The Prime Minister should just do what he promised and deliver the Smith Commission package in full.”

The SNP also urged Labour yesterday to back the devolution of employment and trade union laws.

MPs from both parties have already voted against the Conservative government’s Trade Union Bill, criticising it as “regressive” and an “horrific” attack on workers’ rights.