Why should previous supporters of the Tory party "come home" (?!?) i.e. abando the party that more closely believes what they want; and not previous supporters of other parties do the same ? Or is Cameron simply hoping to return to a possible majority government of whatever flavour rather than make a Tory gain ?
Oh do beware, that link starts playing a video out loud automatically, presumably for a laugh.
How far back would he like folk to return to ? Maybe who they voted for decades ago ? If he wants voters to consider his party the best option he needs to offer what the previous supporters want otherwise they'll vote for one that does.
Sounds to me as if he is rattled. I think he probably doesn't need to be. When no party seems even adequate, the public tends to stick with the status quo.