MI5 chief held up for an hour by airport immigration

Jonathan Evans, who masterminds the country's fight against terrorism, was subjected to the delay at Gatwick, even though he has the highest possible security clearance.

He was held up because only half the booths at passport control were manned, despite a long line of waiting passengers.

The delay suffered by Mr Evans, who was returning from a holiday in Europe, will fuel concerns about the length of airport immigration queues.

The Home Office says British and other EU citizens now face an average wait of only 15 minutes and insists longer checks are needed in the interests of national security.

But the revelation that the Director General of MI5 was forced to wait an hour will raise new questions about the blanket approach taken by the Government and its failure to ensure security checks focus on those who present a genuine threat.

It will also revive concerns about the lack of immigration officers at airports amid complaints from passengers about the number of unmanned booths.

Although Mr Evans would not have revealed his job to officials at Gatwick - or expected any preferential treatment - a witness described the delay as excessive and blamed it on the fact that only half of the passport booths were staffed.

The Immigration Service Union, which represents passport control staff, has warned of increasing delays.

It claims the problem has been exacerbated by the introduction of biometric scanners, which take longer to read passports, and by orders that more rigorous checks should be carried out on all passengers.

Immigration officers would often wave through British citizens after just a cursory examination of their passport but are now required to scan and thoroughly check all documents.

The union says this has resulted in delays of an hour or more for passengers in both EU and non-EU queues at airports including Heathrow, Gatwick, Luton and Stansted.

It argues insufficient extra staff have been recruited to deal with the additional workload.

Passengers, too, have voiced their complaints and told of their growing frustration at the "hassle" at Heathrow and elsewhere when they leave and re-enter the country.

But Brodie Clark, head of border control-at the Home Office's Border and Immigration Agency, has insisted the public supported tougher security checks.

He also disputed that delays were too long and said staffing of immigration booths was sufficient to cope with the growing volume of passengers.

A snapshot survey of passengers arriving at Heathrow over the August bank holiday weekend told a different story, with many protesting about the length of time they had to spend in immigration queues.

Mr Evans took over as Director General of MI5 this year, having previously worked as the security service's director of international counter-terrorism.

He is an expert on tackling al Qaeda and has also specialised in combating the IRA and foreign intelligence agencies.