A tanker driver from Stockton-on-Tees is facing a lengthy jail sentence after admitting killing a father and son by ramming into the back of their horse-drawn caravan.

Gerald Norman Grange, 50, of Norwood Close, Stockton-and-Tees, pleaded guilty at Carlisle Crown Court today to two charges of causing death by dangerous driving.

The home-made caravan - built of plywood and canvas on a metal chassis - disintegrated when Grange's 16-ton lorry ploughed into the back of it at more than 50mph.

Stuart Nicholson, 43, who was walking alongside his horse, leading it by its bridle, died instantly.

His six-year-old son Connor, who was sitting in the caravan painting in a colouring book, was also killed.

The horse was mortally injured and had to be put down by a vet.

The horrific accident happened on June 10 last year just after the caravan had emerged from a slip-road onto the A66 at Coupland Beck, near Appleby, as Mr Nicholson and Connor were making their way home to County Durham after spending the day at the Appleby horse fair.

For some reason Grange, who was driving on the inside lane of the dual carriageway, failed to see the caravan, even though on that stretch of road it would have been clearly visible from about 250 yards away.

The tanker lorry, owned by PD Logistics, was empty at the time.

Grange was due to go on trial yesterday, having previously pleaded not guilty to both charges.

But shortly before the trial was due to start he changed his pleas to guilty.

His barrister John Elvidge said he had pleaded guilty on the basis that he had not been using his mobile phone immediately before the crash - a claim that the prosecution would have made in the trial.

Prosecution counsel Chris Stables accepted the pleas on this basis, saying that although evidence showed Grange had made two calls - neither of which had been answered - in the minute before he dialled 999 after the crash, it was not certain whether those calls had been made while he was still driving.

Grange was remanded on bail for background reports and will be sentenced in the week of July 26.

Judge John Milford warned him that prison was inevitable.

"The sentence that will be passed upon you in due course will inevitably be a sentence of immediate custody," he said. "Custody it will inevitably be."

The judge then expressed his sympathy to Mr Nicholson's family, some of whom were in court.

"I would like to express to them the court's condolences for the dreadful loss they have sustained," he said.