THERE were audible gasps in the House of Commons yesterday as Home Secretary Theresa May admitted that we will never know how many people entered Britain without being checked against a database of terror suspects and illegal immigrants.

There will also have been gasps of disbelief around the country that such a fundamental breakdown in national security could happen without ministerial approval or knowledge.

At the heart of the scandal is the assertion from Mrs May that senior Border Force officials took it upon themselves to extend a pilot scheme she had authorised in April.

If official inquiries show that civil servants took such a momentous decision in defiance of the Home Secretary’s orders not to widen the scope of the pilot scheme, their heads will clearly have to roll.

But there is also a question over why less stringent border controls were being tested in the first place at a time when we are told that the terror threat remains high.

Mrs May gave the go-ahead for a trial in which the gates to Britain were at least temporarily opened wider and, by doing so, didn’t she send a dangerous signal that softer security measures were acceptable?

The Government faces claims that staff shortages, caused by cost-savings in the UK Border Agency, were the root cause of the security breach.

If those allegations are substantiated, the Home Secretary – and the Prime Minister – will have very serious questions to answer about the wisdom of gambling with Britain’s security.