City firm Withers was ‘in contempt’ of parliament when it threatened an MP with legal action if he criticised one of its clients in the House of Commons, a parliamentary investigation found last week.

But the report of the standards and privileges committee says no further action should be taken as the firm had ‘apologised unreservedly’ to the House and to John Hemming (pictured), the Liberal Democrat MP concerned.

The issue arose out of a planning dispute in the MP’s Birmingham Yardley constituency. Hemming had called for a parliamentary investigation after receiving an email from Withers asking him not to repeat in the House or elsewhere allegedly defamatory comments about one of its clients made in a Liberal Democrat leaflet.

The email said that unless the firm received an undertaking not to repeat the remarks, it would ‘have no alternative but to issue proceedings’.

Following an emergency debate in the House of Commons, the committee received written evidence from Hemming, Withers and the Law Society. It concluded that the evidence was ‘clear’ that Withers was ‘in contempt of the House’ and said that contempt had been ‘repeated’.

The committee said the firm had not taken the opportunity to withdraw the contempt: ‘We are surprised that a firm of the standing of Withers should have taken so long to understand the scope of parliamentary privilege.’

In a statement the firm said: ‘Withers is pleased that the committee for standards and privileges has accepted our full and unreserved apology to both the House and Mr Hemming with respect to this matter.’

Parliamentary privilege is a complex area that would benefit from clarification, the statement added.

In a letter to the committee, Law Society president Robert Heslett called for a review, saying there was a conflict between parliamentary privilege and the rights of citizens to defend themselves against defamatory allegations.