Britain has been warned it is defenceless against a potential Iranian missile attack as the state of the country’s air defences is branded “shocking” and “shameful”. Israel on Saturday warned Tehran has developed intercontinental ballistic missiles capable of hitting London following a failed attack on the joint UK-US Diego Garcia base on the Chagos Islands, some 2,400 miles away from Iran.

One missile was shot down by a US warship, while the other failed mid-flight. The UK’s only defence against ballistic or hypersonic missiles is the Royal Navy’s six Type 45 destroyers. Only one is believed to be operational in UK waters, with four out of service and the final ship, HMS Dragon, en route to Cyprus in response to a drone strike on an RAF base on the island.

Sean Bell, a former RAF air vice-marshal, told the BBC: “The worry here is that if Iran was to launch a ballistic missile that was heading our way, unlike Israel, unlike America, unlike Diego Garcia, we have no defences against that in this country.

“Whilst we could track it, it would be able to strike us. Now, I think the chances of that happening are fairly slim.”

He added: “Unless a Type 45 [destroyer] happened to be sailing by, and it is unlikely to be in the right place at the time, the fact remains we have no missile defence against ballistic missiles in this country.”

A senior defence source, with an understanding of the UK’s air defence systems, told The Telegraph: “It’s woeful… combating ballistic missiles are long learned skill set and the UK’s set of those skills is, sadly, very, very low.”

Iran’s attempted attack on Diego Garcia has raised concerns that Tehran has missiles that can travel further than previously acknowledged — or that it had used its space programme for an improvised launch.

Lieutenant General Eyal Zamir, Israel Defence Forces chief of staff, said the missiles had a range of 4,000 kilometres (2,485 miles) — significantly more than the previous max range of 2,000 kilometres (1,242 miles) that many believed Iran had in its arsenal.

London is 4,425 kilometres (2,750 miles) from Iran, but analysts fear Iran could use its Simorgh space launch technology to extend its missile range further.

The Navy’s only operational Type 45 destroyer in the UK is HMS Dragon, which is currently stationed in Portsmouth, over 100 kilometres (roughly 62 miles) from the capital.

The ship’s Sea Viper surface-to-air missile system can take out targets at around 70 miles away.

In a stark warning, former Army officer Philip Ingram told The Sun: “London has got zero ballistic missile coverage at the moment.

“London is naked at the moment.”

Depending on how much further Iran could extend its missile range, major cities like Birmingham and Manchester would also very likely be horribly exposed to potential attack.

It means Britain would have to rely on its NATO allies in Europe to down an Iranian missile as it travelled past alliance air defences on the continent.

Iran on Friday warned British lives are “in danger” after a Government decision to allow US forces to use UK bases — including Diego Garcia — to launch strikes against Iranian missile sites targeting the Strait of Hormuz.

It is understood Iran launched the missiles at Diego Garcia prior to ministers giving the US permission for further strikes on Friday afternoon.

Iran has also threatened to target tourist hotspots as the conflict in the Middle East continues to rage.