But government says security was priority.
After two days of tube strikes affecting London, airports and seaports were hit by an IT glitch yesterday that led to Britain doing even more of what it's best at - queuing.
Foreign travellers found themselves forced to partake in the nation's least popular pastime after a malfunction on UK Border Force computers led to huge delays in passport queues at Heathrow, Gatwick, Stansted and Birmingham airports.
The computer glitch meant immigration officers had to carry out passport checks manually, causing up to four-hour passport queues miles in length at Heathrow, while reports of fights breaking out at Gatwick emerged as England suffered travel chaos.
So far the Home Office has refused to reveal what the IT problems are, with a spokeswoman telling CBR she could not go into "the ins and outs" of the issue.
Compuware's IT expert Michael Allen, VP of application performance monitoring, landed in Heathrow from Europe last night to find himself right in the middle of the problems, and slammed the airport for an apparent lack of contingency plans.
He said: "It was crazy. Quite simply it's not acceptable for IT problems to cause this level of pain.
"IT systems have become more complex in recent years and it seems this complexity is increasingly leading to problems like this.
"IT teams should have the processes, techniques and tools in place to proactively avoid these problems. They should be able to see potential problems bubbling up and deal with them before it gets to the point it did last night."
He claimed thousands of weary travellers were moving "at a foot a minute" in the queue to get their passports stamped.
Frustrated passengers took to Twitter to vent their anger - and they had plenty of time to compose their tweets.
Ella Mason tweeted: "Has Nigel Farage taken a job at the UK Border Agency? Queue at Heathrow 4 immigration as soon as we've got off the plane. 1000s of people trapped. Boiling hot. No information."
Emmanuel Seigner wrote: "Massive queue. Welcome to the Uk #fail #insane."
Heathrow staff handed out bottles of water to the waiting travellers.
Immigration minister James Brokenshire, who visited Heathrow this morning, said that while he regretted the issue, staff were right to prioritise security.
He added: "Our engineers have been working through the night to fix the temporary IT problems that regrettably led to longer queues for some passengers at passport controls yesterday.
"The current situation is much improved and we are doing our best to keep waiting times to a minimum during this morning's busy period."