Westminster could be pedestrianised in a bid to ward off vehicle attacks – terrorists’ “weapon of choice”, Britain’s most senior police officer said.

Metropolitan Police Commissioner Cressida Dick praised officers’ courage as they leapt into action following the “ghastly” crash at the Houses of Parliament.

A 29-year-old man was arrested on suspicion of preparing an act of terror after crashing a silver Ford Fiesta on Tuesday morning.

Over the past year and a half Westminster has become a target for attack for a variety of motivations, including terrorist, Ms Dick said.

She said: “You will notice that the security around parliament both in terms of armed officers and police officers and physical barriers has been further enhanced over the last several months and there is more to come on that in further months.

“Whether that area outside should be pedestrianised further, there should be further physical works done, I think is a matter that will be discussed no doubt between parliamentary authorities, us, the intelligence agencies and indeed the local authorities and the mayor.”

She appealed to anyone with information about the background or events of Tuesday to come forward.

Westminster car crash
Armed police on Victoria Embankment in Westminster (Stefan Rousseau/PA)

She said: “Sadly the vehicle appears to, in some ways when you look across Europe and the western world, have become a weapon of choice, method of attack of choice for terrorists, and devastation can be caused by a vehicle as we’ve seen so many times.

“A horrible attack yesterday, my thoughts are with the people who were injured and the people who witnessed it.”

Ms Dick said there may be an update on the investigation later on Wednesday.

The commissioner added: “As with anything there is a balance to be drawn. Vehicles are on our streets all the time, we have crowds on our streets as well.

“Terrorists want us to completely change our way of life, they want us to be afraid and they want us to stop doing what we want to do to lead a normal life in the UK.

“We are not going to give in, we are not going to just change our lifestyle, but it is important we take reasonable measures, as I think we have being doing over the last several months, to try and make sure that the most iconic sites, including those in central London, are well protected and should something happen there, that the police are able to respond very quickly with armed officers, which is exactly what we saw yesterday.”

The commissioner was speaking ahead of a series of dawn raids – unrelated to Tuesday’s Westminster incident – that took place in Lewisham, south-east London, on Wednesday.

One man, 36, was detained after he had spent the night tucked up in bed with a hunting knife.

Eight men were arrested during raids on eight properties, with a number of weapons and drugs seized.