The mutual’s February house price index showed the fall of 0.2% in January appears to be a one-month hiccup in a stream of otherwise steady increases since the housing market re-opened.

Overall, prices have risen by 6.9% or £15,000 in cash terms since February 2020 – the last month wholly unaffected by Covid-19.

Nationwide’s house price index is based on data at the mortgage approval stage.

Nationwide chief economist Robert Gardner said the February increase was a “surprise” as it expected house price growth would soften further ahead of the stamp duty holiday deadline.

“While the stamp duty holiday is not due to expire until the end of March, activity and price growth would be expected to weaken well before that, given that the purchase process typically takes several months,” he said.

“It may be that the stamp duty holiday is still providing some forward momentum, especially given the paucity of properties on the market at present. Shifts in housing preferences may also be providing a more significant boost to demand, despite the uncertain economic outlook.”

Gardner added that all this meant the outlook for the housing market was unusually uncertain.

“There is scope for shifting housing preferences to continue to boost activity, especially if there is further policy support in the Budget,” he added.

“Nevertheless, if labour market conditions weaken as most analysts expect, it is likely that the housing market will slow in the months ahead.”

Industry commentators noted that the figures suggested the desire to move home was outweighing other considerations.

But they added that expected announcements in the Budget tomorrow about an extension to the stamp duty holiday and other housing policy measures would be crucial in how the market evolved.