A major getaway for the summer holidays began today but hundreds of air passengers faced delays at Luton airport following the arrest of a man in a security incident.
The man was being held in custody after trying to take an illegal substance on a plane.
The substance, discovered in the baggage area, was thought to have contaminated bags being loaded on to a plane operated by Monarch Airlines.
This plane was stuck for some time on the runway and check-in was suspended at the Bedfordshire airport.
Police said it was not yet known what the substance was but it was "not thought to be a terrorist threat".
The Luton passengers were among an estimated 1.9 million who will be travelling abroad over the period from today until Monday.
A total of around 440,000 were leaving from Heathrow airport, 250,000 from Gatwick, 139,000 from Stansted, 65,000 from Birmingham, and 65,000 from Luton.
Also, 127,000 will leave from Edinburgh and Glasgow airports.
Travel organisation Abta said top destinations for short-haul holidaymakers included Turkey, Greece, Egypt, the Canary and Balearic islands and mainland Spain.
Popular long-haul destinations included Dubai and Florida.
Abta chairman John McEwan said: "I am delighted to see hundreds of thousands of us heading overseas this weekend - the traditional curtain raiser to the summer season.
"With prices having fallen in the eurozone and an improved exchange rate on last year, holidaymakers will get a pleasant surprise when they arrive in resort and head for local restaurants and bars."
A survey by Co-operative Travel of more than 3,500 bookings has revealed that the prices for family holidays have fallen by as much as 34% since last summer.
The biggest savings are to be found in eastern Mediterranean resorts, in particular Paphos in Cyprus (a 34% fall), Crete and Zante in Greece, and Turkey (24%).
On average the price of a family holiday across the top 20 destinations for UK holidaymakers has fallen by 13.5%, representing a typical saving of £232.
The AA predicted today would be the busiest Friday of the year for traffic, with 14 million cars likely to take to the roads this weekend.
It added that routes to south-west England are expected to be the most congested.
The AA pointed out that drivers planning to travel southbound on a section of the M6 in the West Midlands should be aware that it will be closed from 10pm tonight until 8am tomorrow and from 8pm tomorrow until 10am on Sunday from junction 11 (Cannock, Wolverhampton) to junction 7 (Great Barr interchange).
On the London Underground, sections of the Hammersmith & City and Circle lines between Hammersmith and Edgware Road in west London are closing from tomorrow until August 15 due to construction of the cross-London Crossrail project and Tube station upgrade works.