A lorry driver was arrested yesterday after a father and son were killed when a 38- tonne tanker collided with their horse-drawn caravan.

Stuart Nicholson and his son, six-year-old Connor, were killed when they were hit while travelling home from a horse fair.

The driver of the tanker was arrested on suspicion of causing death by dangerous driving.

He has not been named but is aged 50 and comes from Stockton.

Mr Nicholson and Connor were returning to their home in Wheatley Hill, County Durham, from Appleby Horse Fair, in Cumbria, when the tragedy happened.

They were travelling along the A66 near Appleby, at 6pm on Tuesday, when their caravan collided with the articulated tanker, which was travelling in the same direction.

Cumbria Police said 44-year-old Mr Nicholson and his son died instantly. Their horse was later destroyed.

Mr Nicholson had two daughters, Sarah, 17, and Nicola, 15. They were being comforted by relatives at their grandmother's home in Wheatley Hill.

Mr Nicholson's sister, Margaret, said: "We were worried about where he was so we phoned the police and they told us. We still don't have any idea about what happened or the lorry that hit them."

The Nicholson family had lived in Caine Terrace for more than five years.

Neighbour Laura Hutchinson, 19, said she was very upset about what had happened and told how the Nicholsons went to Appleby Horse Fair regularly.

Connor was a pupil at Wheatley Hill Primary School. Mr Nicholson owned riding stables and had his own horses.

He and Connor had been at the fair and were travelling in a traditional-style caravan.

More than 12,000 horse fans and travellers from across the world attend Appleby Horse Fair every year. John Twinks, who owns the Appleby Fair Company that makes merchandise for the event, said: "For a thing like this to have happened is an absolute tragedy.

"There is always a big risk of accidents when people are travelling on main roads in traditional caravans, especially with all those wagons you get on the A66.

"It is absolutely horrendous travelling up. Only this morning we were nearly wiped out by a wagon."

The fair's organisers had spent a long time this year altering the programme in an effort to reduce the danger visitors faced from the traffic and the horses.

Inspector Paul Coulson, of Cumbria Police, said: "About 11,000 gipsies come to this area from all over the country at this time of the year for the Appleby Horse Fair. Some hire these traditional caravans for the event."

The dual carriageway was closed in both directions for five hours after the accident.