HIGHWAY robbery 1993-style has arrived in Britain with an assault and theft of GBP70,000 (HK$819,000) of jewels from a woman held up on the country's busiest motorway. Mina Mullins, 41, was driving her Mercedes 500SL sports car down a slip road off the M25 London orbital motorway when her vehicle was rammed from behind. As she stopped to check the damage the two Asian men beat her about the face, head and body and snatched the jewels she was wearing before making off in the GBP75,000 car. The British press has carried several reports recently of this sort of crime in France and the United States but it is the first time it has been documented in modern times in Britain. Mrs Mullins, whose husband was away on business in the Philippines, was driving back from a party at London's exclusive Dorchester Hotel to her home in Wentworth, Surrey, when the gang struck. The men attacked her as soon as she stepped out of her car. ''They started coming forward, one behind me, one at the side,'' she said. ''The driver, who was issuing orders and was more in command, took a gun and put it to my forehead.'' She was then repeatedly beaten with the gun before the men tore off her jewellery, including a GBP50,000 diamond ring. Her husband has offered a GBP20,000 reward for information leading to the robbers' conviction.