Committee of MPs indicate that age-old practice of seeking royal consent for parliamentary bills may soon come to an end

A cross-party committee of MPs has questioned whether the Queen and the Prince of Wales should keep a residual power of veto over certain parliamentary bills.

MPs on the Commons political and constitutional reform committee said the royal process of consent fuels speculation that the monarch "has undue influence on the legislative process".

Under a convention dating back to 1728, the monarch must consent to any parliamentary bill affecting the crown. The Prince of Wales does the same for bills affecting the Duchy of Cornwall.

The MPs highlighted the way in which the Queen's solicitors, Farrer & Co, have to be copied in to all correspondence seeking consent. They said: "The process of consent is complex and arcane and its existence, and the way in which the process operates, undoubtedly does fuel speculation that the monarchy has an undue influence on the legislative process."

But the members were unable to cite examples where the Queen or Prince Charles withheld consent. Andrew Lansley, leader of the Commons, said a request for consent was effectively a demand by ministers for agreement from the monarch or her heir. "A request for consent carries with it by implication ministerial advice that consent should be granted," Lansley said in written evidence.

The MPs on the committee said it is the government, rather than the monarch, which can use the process of consent to block a bill. Prof Rodney Brazier of Manchester University told MPs he could think of four examples between 1868 and 1999 when the government used the process to block a private member's bill.

In the most recent example, the then Labour MP Tam Dalyell said Tony Blair's government had advised that royal consent should be refused in 1999 over his bill to ensure military action could only be taken in Iraq with parliament's approval. The then government is likely to have argued that Dalyell's bill would have curbed the royal prerogative – the monarch's power, exercised by the PM, to declare war.

MPs are usually informed at the third reading stage whether consent has been granted. This is separate to the royal assent, which turns a bill into law after it has passed all its parliamentary stages.

The committee indicated that the time might be approaching when the practice should end. This could be decided by parliament and would not need a law change.

The MPs said: "The United Kingdom is a constitutional monarchy. The Queen has the right to be consulted, to advise and to warn. But beyond that she should have no role in the legislative process. Consent serves to remind us that parliament has three elements – the House of Commons, the House of Lords, and the Queen-in-parliament. Its existence could be regarded as a matter of courtesy between the three parts of Parliament. Whether this is a compelling justification for its continuance is a matter of opinion."