David Cameron's awkward Alex Salmond joke caught by This Morning microphone

A recurring theme of the Conservative Party's general election campaign has been warnings of what an alliance between Labour and the Scottish National Party could mean for the UK.

A campaign poster famously/infamously portrayed Labour leader Ed Miliband being in Alex Salmond's pocket, despite Nicola Sturgeon being the SNP leader.

Defence secretary Michael Fallon said Miliband would betray Britain over Trident just like he "stabbed his own brother in the back", while this week former prime minister Sir John Major said the SNP could "blackmail" a future Labour government.

In the leaders' debates meanwhile Sturgeon offered an olive branch to Miliband to "lock David Cameron out of Downing Street".

If you thought that we were approaching peak tension between the SNP and the Tories you'd be wrong, however.

Today, in an appearance on ITV's This Morning - yes, the PM didn't want to do more than one debate but was happy to be on the sofa with Phillip Schofield and Amanda Holden - Cameron made a joke that he might not have wanted to be picked up by the microphone.

Schofield was introducing the next segment, an interview with pickpocket entertainer James Freedman, a man who "can pinch your wallet, your watch and even your tie without you ever noticing".

As the preview pictures played, Cameron can be heard remarking: "Is that Alex Salmond?"

Watch it here:

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