Security measures have been tightened at a Winchester jewellers after a man with a missing tooth snatched a £30,000 diamond ring.

The drama happened on Tuesday afternoon when 44-year-old proprietor, Jeremy France, ignored all the training and "had a go", running up the High Street after the thief.

"My staff are told not to give chase but I'm the boss so I can do what I want," he said.

Unfortunately, the man's trainers gave him a distinct advantage and Mr France, who was wearing leather shoes, took a tumble on the corner of Tower Street and could only watch as the thief jumped into a waiting white M-reg Ford Mondeo which sped away, wheels spinning.

"I nearly got him," said Mr Francis, who had been alerted by the screams of an 18-year-old assistant who had been showing the ring to the man - store CCTV images have been given to Winchester police.

Mr France said the stolen ring was unique - the most expensive one to be displayed in the 13 years he has operated the business.

It has three diamonds set in platinum - a rectangular two-carat Phoenix cut with 89 facets, instead of the conventional 58, flanked by pear-shaped white diamonds, totalling 0.34 carats.

The thief is said to be in his mid-20s, 5ft 10ins, white, with short, brown hair and missing an upper right front tooth.

Police are appealing for witnesses - ring 08450454545 if you think you can help.