An Iranian ballistic missile could reach Britain and strike London because the county is so badly defended, it was claimed on Monday night.

The shock prediction came after the Defence Secretary finally admitted Tehran’s long-range missiles targeted the UK base on Diego Garcia in the Indian Ocean.

One of the rockets aimed at the UK-US airbase failed in flight. The other was hit by a US interceptor fired from a warship. The attack happened between Thursday night and Friday morning yet it was only acknowledged officially for the first time on Monday.

Experts dismissed the Prime Minister’s reassurances that Britain has ‘very effective ways of defending itself’ on Monday night.

Former Army intelligence officer Phil Ingram said: ‘Look at London, there is no air defence. We have very limited anti-drone capability and even less anti-cruise missile capability. 

‘Our Type 45 frigate does not have advanced ballistic missile capability and cannot cover the whole of the UK.

‘There’s only so much the RAF’s Quick Reaction Force can do.’

Mr Ingram also accused Defence Secretary John Healey of using a misleading phrase by describing the UK’s anti-missile defence as ‘layered’.

Royal Navy destroyers are equipped with the Sea Viper missile system which experts believe would prove effective against ballistic attacks.

Defence Secretary John Healey came under fire for describing the UK’s anti-missile defences as ‘layered’

Former Army intelligence officer Phil Ingram said London has ‘no air defence’ and has ‘very limited anti-drone capability and even less anti-cruise missile capability.’

But according to military expert Michael Clarke, formerly of the Royal United Services Institute, the UK’s air defences are ‘bits and pieces’.

He said: ‘Air defence is very expensive and traditionally we haven’t done it.

‘We have tried to deter, through our nuclear deterrent, rather than to defend. It is a bits and pieces defence.

‘We claim it is multi-layered but we would need a ring of ten to 15 destroyers, rather than two, to defend Britain’s eastern coastline.’ 

Mr Healey told the House of Commons how air defences were ignored by previous governments. Now officials have been granted permission to spend an additional £1billion on that area.

Mr Healey also confirmed the only warship the Ministry of Defence has committed to the Iran security crisis, HMS Dragon, has finally sailed into the eastern Mediterranean.

Appearing before a Commons committee yesterday, Sir Keir Starmer was asked whether the UK could defend itself.

He said this was ‘constantly assessed’ and added: ‘I can tell you our military personnel, our security and intelligence services are working 24/7 to keep us safe and do a very good job in that regard.’