Two men on a touring holiday of Britain were injured by an explosion in their motor van in the centre of Norwich yesterday. Shoppers, traders and businessmen in Red Lion Street were shocked by a loud bang, and seconds later the two men jumped over from the vehicle, which had stopped outside Barclays Bank. Several people rushed to give assistance and helped to put out the fire inside the vehicle, a light American truck converted to provide living accommodation, before Norwich firemen arrived. The men--American Mr. Gary House, aged 25, of Ohio, who was driving, and his passenger Mr. Charles Lynn, 23, of Vancouver--were taken to Norfolk and Norwich Hospital with minor bums. They were allowed to leave after treatment. 'I heard this explosion, it was pretty loud. I thought it could have been a bomb.' Said Mr. Webster, manager of the market, who was working in his office in Red Lion Street. 'I looked out of the window and saw this lad leap from the van and roll on the ground. Then another lad came out of the van. He seemed to be in a worse state--parts of his trousers were hanging below his knee.' 'I came downstairs to get a fire extinguisher, but by the time I got outside someone from the bank was in the van with an extinguisher.' Mr. Webster, who lives at 71, Trinity Street, Norwich, said both victims were shocked. One was taken into the market office to await an ambulance. 'The second men insisted on going back into the van to see if everything was all right, and five minutes later he came out with a drawer that was blazing,' he added. The explosion was also heard inside the bank. Staff provided a fire extinguisher and telephoned for an ambulance. Although a plastic window was blown out, damage inside the vehicle was mainly superficial. The two men spent the last six months touring the Continent and had traveled to Norwich from Sheterton. At the time of the accident their wives were shopping in the city. The two men in the van _____.