Further evidence has emerged that a desire to impose a new tax on family homes could form the basis of the agreement between Labour and the Scottish National Party, leading to a 'Frankenstein coalition'.
The Scottish Labour leader, Jim Murphy, has announced that Labour want to provide £1 billion extra for Scotland's NHS by taxing more than 100,000 homes in London and the south-east of England.
Murphy said he would make "no apology" for using money "gathered" from the South East to fund the additional spending over the next parliament.
He published an analysis showing Labour's tax on homes worth more than £2 million would affect fewer than 900 properties north of the Border, about only 0.8 per cent of those liable across the UK.
Scottish 'mansions' would generate around £5.5 million per year under the levy, only 0.3 per cent of the estimated £1.6 billion the levy would be expected to raise across the UK.
According to figures obtained through the property website Zoopla, 99,722 of the 108,477 homes (92 per cent) that would pay the levy are either in London or the surrounding area. Those homes would provide 95.9 per cent of the total proceeds from the tax. However, about 10 per cent of the money raised would go to the Scottish Parliament thanks to the Barnett formula, which gives Scots £1,200 more per head of public spending than the UK average.
Meanwhile, the SNP has long been committed to its own version of a 'mansion tax' through a sharp hike in Scottish stamp duty. In October 2014, SNP Finance Secretary John Swinney revealed that his replacement for stamp duty would mean the levy on the purchase of homes worth more than £250,000 would increase by 10%.
At the time of the SNP announcement, Paul Gallagher, tax partner and head of Ernst and Young Scotland's government and public sector practice, claimed SNP ministers were effectively proposing a mansion tax - a scheme which had the "potential to tighten the screw on the 'squeezed middle'".
With both Labour and the SNP committed to the idea of taxing higher value properties, it is now feared that a coalition between the two parties, which could result from a hung parliament, would likely lead to hefty new taxes on people's homes.
Responding to Jim Murphy's announcement, Conservative Candidate for Chelsea and Fulham, Greg Hands said: "It is clear that both Labour and SNP have an ideological bent for wanting to tax people's homes, which they will be only too keen to implement given the chance of forming a coalition or some other arrangement together. This would be some kind of tax-hungry Frankenstein coalition between SNP and Labour.
"It's small wonder the SNP and Scottish Labour are so keen to impose taxes on family homes - they know that, due to the lower land values, many Scottish homes would be exempt from it - even grand country mansions and castles - while ordinary homes in London and the South East would be left to shoulder the burden. Jim Murphy's recent comments only serve to further highlight the absurdity and unfairness of this proposed new tax.
"As one constituent of mine recently emailed me: 'Why is it that a Laird in Scotland with a twelve bedroom MANSION, staff and a Gillie, do not have to pay its tax, but a hard working family living in a terraced house in Hammersmith and Fulham is penalised?' - He makes a good point.
"Such a policy would be particularly damaging in my constituency of Chelsea and Fulham, which has some of the highest land values in the country, and which estate agents have predicted would be the second worst affected area in the UK for Labour's 'Homes Tax'. Many properties in Chelsea and Fulham which cost £2m, far from being 'mansions', are in fact flats or small houses. This would be introduced as a 'mansion' tax, but this is really a 'homes tax'. Once in place, people might suddenly find that their modest home has been classified as a 'mansion'.
"I have opposed the idea of Labour's homes tax since it was first proposed, and the Chancellor has confirmed that the Conservatives will not be introducing any such tax. Voters have a clear choice at this election between low taxes and economic security of David Cameron and the Conservatives, or of the chaos of Ed Miliband's Labour, propped up by the SNP."