Britain is bracing itself for a blast of Easter snow that promises to dampen seasonal celebrations and prolong the motoring misery for millions.

Forecasters issued a warning that snow showers would affect large parts of the country. With up to 16 million vehicles expected on the roads during the weekend, the Highways Agency has urged drivers to take extra care.

The numbers on the road are expected to be swollen after Network Rail began a “huge” engineering work programme, which crippled parts of the rail network.

Timetables on some of the busiest routes were slashed to one train an hour or fewer as operators ran weekend services to allow track-laying and bridge repair work.

Thousands were caught in delays on motorways across Britain yesterday despite the removal of roadworks by the Highways Agency on many main routes.

A fatal crash on the M25 on Thursday afternoon forced police to close a long stretch of the road for eight hours. A car passenger died after the vehicle collided with a lorry. The accident resulted in long tailbacks and caused delays to flights from Gatwick as travellers and staff struggled to reach the airport.

Yesterday queues of up to three miles formed at Dover as freight lorries and holidaymakers attempted to catch ferries across the Channel.

On the M3, several vehicles crashed into each other during a heavy downpour shortly before 7am, forcing the closure of the southbound section for several hours. Minutes later paramed-ics and police were called to two crashes in Hampshire, also leading to road closures.

In case of severe weather this weekend, the Highways Agency has advised motorists trapped in their cars to turn off their engines and stay in their vehicles.

Paul Fox-Hughes, national forecaster at the Met Office, said: “Large parts of the country will get a white Easter. There is a fairly significant risk of bad weather, particularly in the east of the UK, with a band of snow showers affecting parts of northeast and eastern England and down to parts of the Midlands.

“We will see a couple of centimetres of snow on lower parts of the country and about 15cm (6in) on ground above a few hundred metres.

“Another band of snow showers is likely to move in today and tomorrow so there will be more snowfalls. Temperatures are a few degrees lower than normal for this time of year, so on Saturday and Sunday it will be about 5C to 7C.”

Elliott Frisby, spokesman for Visit-Britain, the national tourism agency, said: “We think an extra half a million people will travel in Britain this weekend compared with last year. As Easter is early this year, a lot of schools aren’t having their holidays until April so people are more likely to stay in Britain for a short break.

“The weather makes it more of a challenge but remember that we do have a lot of indoor attractions in Britain, which I suspect will be popular.”

While the Highways Agency is removing almost two thirds of roadworks from motorways and major A roads for the holiday getaway – 47 have been suspended until midnight on Monday – Network Rail pressed on with its engineering programme.

As well as on main lines, work was being carried out at Clapham Junction and Liverpool Street in London.

Moveable feast

— The last time Easter fell this early was in 1913. It will next be this early in 2228

— Next year, Easter will fall on April 12

— The problem of fixing the date of Easter dates back centuries

— Christians of Jewish origin celebrated the Resurrection immediately after the Passover festival using their Babylonian lunar calendar, so Easter fell on different days of the week

— Christians of Gentile origin wished to commemorate the Resurrection on the first day of the week, Sunday, so Easter always fell on the same day of the week but on different dates

— The Roman Emperor Constantine I’s Council of Nicaea ruled in 325 that the Easter festival should be celebrated throughout the Christian world on the first Sunday after the full moon following the vernal equinox

— The council also decreed that if the full moon occurs on a Sunday and coincides with the Passover festival, Easter should be the following Sunday

— Since 1752, when the Gregorian calendar was adopted in Britain, Easter has been celebrated on the same day in the Western part of the Christian world

— Passover falls on the 15th day of the month of Nissan on the Jewish Calendar. To keep the calendar in tune with the seasons of nature, every few years Judaism inserts a “leap month” or a second month of Adar. This year is one of those years and so the Jewish Passover and Christian Easter are rather far apart. This year, Passover begins at sundown on April 19. It will be back to normal in 2009

Source: Times database

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