Nigel Farage MEP, whose fiery Euroscepticism has helped his party overtake the Liberal Democrats in recent polls, said the people of England, Wales and Northern Ireland would not want to hand over a "fat cheque" if Scotland chose to quit the UK.
He told the Sunday Herald he had no issue with Scotland deciding its own destiny, but that this was not the same as granting the First Minister's every wish in negotiations with Westminster.
If there was a Yes vote, talks between Edinburgh and London – including those on how to divide the UK's assets and the national debt – would start during the 2015 General Election campaign. If Ukip pushed for the rest of the UK to get the best deal possible for its citizens it would upset Salmond's hopes of a smooth transition, and might mean David Cameron taking a similar hard line for fear of losing more Tory voters to Ukip.
Farage said: "It seems to me a remarkably naive approach for the SNP to think a post-independence rump government of the UK would just say 'Tally ho chaps, here's a big cheque'.
"It may be that people like Mr Cameron, Mr Miliband and Mr Clegg would like that to happen.
"But can you imagine the reaction from the English electorate? It would show yet again how out of touch they are in the political class.
"There would be an enormous political reaction, and not just in the Tory shires, but across the country. If they think gay marriage is an issue, it will pale into insignificance compared to that.
"While the political class might want to pat Alex Salmond on the back, there's absolutely no way that the people of Wales, England and Northern Ireland would be happy with that – of course they wouldn't.
"And to think that they might just ignore it is daft. It's naive in the extreme."
Although a Little Englander approach would finish Ukip in Scotland, no party with UK in its name was ever likely to be particularly active in Scotland after a Yes vote.
The SNP described Farage's comments as "bizarre".
A spokesman said: "Scotland already more than pays its own way, and on independence will inherit its share of the assets and liabilities of the UK.
"Ukip has repeatedly failed to make any impression in Scottish politics, which is no surprise given Mr Farage seems so out of touch."