A former senior London police officer has raised concerns that there was a “reduction” in the number of armed guards at the gates of Parliament where the Westminster attacker struck.

Peter Kirkham pointed to reports that the officer who gunned down attacker Khalid Masood was the personal bodyguard of Defence Secretary Michael Fallon, who it is claimed was only on the scene coincidentally.

His intervention raises questions over whether the knifeman who stabbed and killed unarmed PC Keith Palmer on Wednesday, may have killed more had the bodyguard not been on hand.

It also comes against a backdrop of a 25 per cent fall in the number of Metropolitan Police firearms officers since 2010.

After Prime Minister Theresa May stood in the House of Commons and told how the Government has boosted police spending, former Met senior investigating officer Mr Kirkham refuted her claim.

He said: “I’m beginning to hear that there’s been a reduction [of armed officers] at the Houses of Parliament.

“Hence there wasn’t armed officers specifically on that gate yesterday, it was in the presence of that yard. We’ve heard that it was a protection officer that just happened to be there by chance.”

Mr Kirkham added on Sky News: “The security of the Houses of Parliament is going to be reviewed, what really needs to be reviewed is the levels of policing in the whole of the country.”

PM responds to Westminster attacks

A source on Parliament's Joint Committee on Security told The Independent there had been no recent discussion about a reduction in the number of armed officers at Westminster.

Any such reduction would need to be considered first by the committee, the source said, which is chaired by Deputy Leader of the Commons Lindsay Hoyle.

“If there was a recommendation to cut the number of armed officers on the frontline at Parliament, we would be told about it,” he added.

But reports emerged on Thursday that the individual who shot the assailant on Wednesday was Mr Fallon’s Met close protection officer, raising questions as to whether another armed guard would have been on the scene if he were not.

The Met said it would not be appropriate to confirm the identity of any officer involved in a fatal firearms incident.

Official Home Office figures show that the number of Metropolitan firearms officers dropped by a quarter, from a high of 2,856 in 2010, to 2,139 by last year.

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Speaking in the Commons on Thursday morning, the Prime Minister said: “Following the 2015 Strategic Defence and Security Review, we protected the police budgets for counter-terrorism and committed to increase cross-government spending on counter-terrorism by 30 per cent in real terms over the course of this Parliament.

“And over the next five years we will invest an extra £2.5bn in building our global security and intelligence network, employing over 1900 additional staff at MI5, MI6 and GCHQ and more than doubling our global network of counter-terrorism experts working with priority countries across Europe, the Middle East, Africa and Asia.”

She went on: “In terms of security here in Westminster, we should be clear first of all that an attacker attempted to break into Parliament and was shot dead within twenty yards of the gates.