A £1.2billion ‘electronic borders’ system which is supposed to protect Britain from illegal immigrants, terrorists and foreign criminals descended into shambles last night. The Government sacked the U.S.-based firm paid by Labour to introduce the programme after it was hit by chronic delays.

As a result, 100million journeys a year in and out of the UK will continue to go unrecorded by officials in charge of the massive ‘e-Borders’ project. Ministers will also remain unable comprehensively to count people in and out of the country – leaving them in the dark about the true scale of illegal immigration. At the earliest, it will now be 2015 before the UK Border Agency can check and record every arrival and departure.

The e-Borders system had its origins in a grilling of Tony Blair by Jeremy Paxman during the 2005 general election campaign. The then-PM shifted uneasily in his chair while being asked by Mr Paxman – no fewer than 20 times – how many illegal immigrants were in the UK. Pathetically, he was unable to give a satisfactory answer.

The reason, Mr Blair said, was that nobody was counting immigrants in and out of the country, so it was impossible to know precisely who was living here. Thus, Labour began work on the ‘e-Borders’ programme electronically to log every journey in and out of the country.

Five years may have passed since Mr Blair’s humiliation on Newsnight. But if David Cameron were asked the same question today, the answer would be the same: ‘I do not have a clue’.

However, even with its current limited coverage, with only 50 per cent of journeys logged, information gained through e-Borders has led to more than 6,200 arrests – including 46 murderers and 126 sex attackers. The question, given the shambles in the implementation of the programme, is how many more could be slipping through the net.

The coalition is furious because it had been relying on the system working to help implement its tougher border controls and immigration cap. Immigration minister Damian Green said: ‘This Government supports e-Borders, which helps reduce the threat of terrorism, crime and immigration abuse through the electronic collection and checking of individual passenger details against police, security and immigration watch lists.

‘Regrettably, however, the Home Secretary has no confidence in the prime supplier of the e-Borders contract, Raytheon, which since July 2009 has been in breach of contract. ‘With critical parts of the programme already running at least 12 months late, we have taken the decision to terminate the e-Borders contract with them.’

As he revealed the sacking, Mr Green told MPs that £188 million had already been spent on supplier costs.

Britain has not kept complete records of passenger movements since Labour scrapped embarkation controls in 1998.