THE SNP have been given another boost by the latest opinion poll results by Lord Ashcroft.

The constituency polls by the Tory peer puts the party even further ahead than polls earlier in the year and sees it overtake Scottish Labour leader Jim Murphy in East Renfrewshire.

It increased its lead in Glasgow south west, held by Ian Davidson and in Douglas Alexander's Paisley and Renfrewshire South seat.

The polls conducted this month by telephone show in Glasgow South West the SNP polling 55% and Labour on 34% a leap of 18 percentage points from a narrow 3% lead in January.

In Paisley and Renfrewshire South the SNP increased its leaded from 8 to 11 points taking it to 50%.

In Mr Murphy's Seat of East Renfrewshire the nationalists have overturned his narrow 1% lead to a 9% SNP lead and the SNP are now polling 40% to Labour's 31%.

The SNP are also ahead in East Dunbartonshire with Labour in third behind the LibDems who hold the seat with Jo Swinson.

Ashcroft polled in eight marginal constituencies to see if anything had changed and raised the prospect of a Tory tactical vote saving Mr Murphy.

He said: "I wanted to know whether the SNP surge had subsided in places I had previously surveyed; whether it threatened other incumbents, especially Lib Dems; and whether there were any potential surprises in store. The answers are no, yes and yes.

"In the three Labour seats the SNP are further ahead than when I polled them earlier in the year.

"In East Renfrewshire, the one-point Labour lead I found in February has become a nine-point advantage for the SNP. However, this seat has a bigger Conservative share than many other Labour strongholds (25%), and I found Conservative voters less likely to say they would rule out voting Labour (64%) than would rule out the SNP (87%).

"How many Tories will decide to lend their vote to Jim Murphy to stop the nationalists?"