Nigel Stockton, financial services director of Countrywide, said: “The only over-arching concern I have [about NewBuy] is the lack of clarity on part exchange.
“If NewBuy really is geared towards helping first time buyers and homeowners then part exchange plays a critical role to get the volumes needed in NewBuy take up.”
Stockton said rumours are afoot that the terms are still being thrashed out with developers, the HBF, CML and lenders concerned to find an agreeable solution.
“I hope they do soon,” he added.
A spokeswoman for the CML said: “The agreement between lenders and builders on part exchange is that it will be allowed in the scheme but at the discretion of the individual lender.”
And a spokesman for the Home Builders Federation added: “Though the default position is that part exchange is included in NewBuy it is actually down to each individual lender.
"We will be working hard with lenders to persuade them of the need for part exchange to be eligible as it is a very important part of the current housing market, particularly for people trying to move up the ladder.”
Santander, Nationwide, NatWest and Barclays have all committed to stand behind the NewBuild scheme already.
“While the pricing on some products was disappointing, credit is owed to Nationwide for using intermediaries to rollout NewBuy,” said Stokton.
“I know it is all too easy to knock the efforts of those lenders prepared to step forward show the commitment needed to launch NewBuy but without them there would be no NewBuy.”
Stockton added that Countrywide advisers had already seen “strong appetite” from buyers wanting to benefit from the scheme.
“I sincerely hope more lenders follow suit to ensure they can stomach the strong appetite for NewBuy that we’ve seen and to keep the product pricing competitive,” he said.
