Disgraced former Shropshire MP Derek Conway was today ordered by the Commons standards watchdog to repay £3,757 of taxpayers’ money he used to employ his elder son Henry.

A critical report by the Standards and Privileges Committee found Mr Conway breached parliamentary rules by paying Henry an “unnecessarily high” salary.

The watchdog MPs said it demonstrated “a serious lapse of judgement” and ordered the former Shrewsbury and Atcham MP to make a written apology to the Commons.

Mr Conway was suspended from the House of Commons last year after the committee found he misused taxpayer-funded staff allowances to pay his youngest son Freddie a salary and bonuses while he was a full-time student in Newcastle. He was ordered to repay up to £13,160.

The focus of the committee’s second investigation was on payments made to his elder son Henry, between 2001 and 2004.

He was employed as a research assistant for 18 hours a week and was paid an initial £8,000 a year which was increased to £10,000 a year, plus bonuses totalling £3,838, according to the report.

It means he pocketed a total of £35,744 during the period he worked for his father.

The new report comes a year after David Cameron expelled Mr Conway from the Conservative Party by stripping him of the Tory whip. The Old Bexley and Sidcup MP is now listed as an Independent Conservative. Mr Conway’s case prompted a review of MPs’ allowances and arrangements for employing their staff, leading to much tighter rules on the employment of family members.