Bromsgrove MP Julie Kirkbride’s career was hanging by a thread today as anger grows over her expenses claims.

The under-fire Tory backbencher broke cover to mount a desperate defence of her position after David Cameron warned she had “questions to answer”.

But she was pushed deeper into trouble by revelations that taxpayers part-funded a £50,000 extension at her flat so her brother could live there.

Ms Kirkbride insisted the extra bedroom was needed because it was “inappropriate” for her young son to share with his uncle, who was carrying out childcare duties.

She said the arrangement – which saw her claims for mortgage interest payments rise by around £250 a month – was explicitly authorised by the Commons Fees Office.

Ms Kirkbride has vowed to fight on – although she did accept that the matter could be taken out of her hands.

She said: “I would dearly love to be re-elected to the job that I simply adore and which has been very fulfilling and personally very satisfying for me over the last 12 years, but that is not my decision. If David Cameron asks me to go, then of course I will do as he asks.”

The news came at the end of a third week of controversial disclosures about expenses. Tory grandee Sir John Butterfill became the latest subject today, after avoiding capital gains tax on £600,000 profit from selling a taxpayer-funded property. He claimed nearly £17,000 just for servants’ quarters. He has agreed to repay £20,000 in tax and mortgage payments.