There are predictions that the new SDLT regime will raise house prices.

One accountant said that prices could rise “overnight”.

Account Robert Dowling, of MHA, said: “Purchasers buying houses under £937,500 will now be better off under the new rules which broadly equate to 98% of residential transactions.

“There will, however, be an unintended effect on houses which are valued around the previous boundaries.

“These properties (which have been artificially reduced because of the boundaries) are likely to go up in value overnight and prospective vendors are likely to try and cash in on Stamp Duty savings on offer.”

Zoopla said yesterday that the old ‘slab’ system had distorted house prices to the extent that more than 28,000 properties had been marketed in the year to May at prices just below the thresholds.

The average discount had been £7,455, said Zoopla.

Undoubtedly, some agents will today be poised to revisit their valuations of properties hovering at around the old slab thresholds.

The reforms have, however, been broadly welcomed by agents.

Eric Walker, managing director of Northwood, said: “Frankly, this is what many agents have campaigned for. I can’t believe it has taken so long for common sense to prevail.

“Graduated tax without the ridiculous leaps where a purchase price at £250,000 would be charged at £2,500 yet an extra penny could create an additional £5,000 on the tax bill.

“This is a far better plan than the so-called Mansion Tax which would have been imposed upon people who may not have been able to afford it, forcing them to sell. Just because you own a flat worth £2m doesn’t mean you are cash rich, especially those in prime London who are retired.

“This reform gives people a clear option, enabling them to make an informed choice as to whether they can afford to buy a property and choose to pay the tax or not. I suspect at this price level it will make little difference to buyers who will simply factor it into the price.

“With the vast majority of buyers better off, Mr Osborne may have flummoxed Mr Balls, though many will ask whether such savings can be justified with the increasing deficit and promised increased spend on the NHS.

“What is clear is that the vast majority of buyers due to exchange contracts this week will have received an unexpected Christmas bonus. Whether its good economic policy or just clever politics I shall leave for Robert Peston to decide.”

Mark Hayward, NAEA managing director, said: “The National Association of Estate Agents is very pleased that the Chancellor has listened to our proposal on Stamp Duty and reviewed the cumulative slab system to abolish it and introduce a gradual band tax.

“As the Chancellor said, these measures will help the majority of buyers.

“Only those paying more than £937,500 will pay more Stamp Duty than under the current system.

“Pinch points have been addressed to help first- and last-time buyers and make buying and selling more affordable –the changes will help many first-time buyers to get on the property ladder. In addition, we also expect the changes to help balance the seesaw of supply and demand in the current market.”

However, the changes have caused a collective sharp intake of breath in the London market.

Ed Tryon, of property search agency Lichfields, said the changes were a way of clobbering the rich to butter up middle England voters.

He said: “It is unbelievably damaging to the top end of the prime London market and I am staggered over this increase in the rate.”

Lisa Mackenzie, regional sales director at Kinleigh Folkard & Hayward, said: “Taking away the smaller increments and making one large band between £250,000 and £925,000 will eliminate the stigma previously associated with certain price bands, especially those around £500,000.

“However, the changes do penalise buyers looking in excess of £1m which will disproportionately affect the market in the capital.”

Peter Mackie, senior partner of buying agents Property Vision, said: “Buyers [in London] will have to stump up as much as £100,000 in Stamp Duty for an ordinary Victorian semi-detached home.”