Fortnum & Mason, the prestigious London store, yesterday admitted tourists' buying power had been affected by the strength of sterling on foreign exchanges. Even so, results for the year to July 2 showed pre-tax profits £7,000 higher at £3.227 million with the total dividend increased from 7.6p to 8.3p. The group said after an excellent Christmas trading period when turnover was 11 per cent up on the previous year, sales growth at its flagship London store on Piccadilly fell back to give an annual increase of just 1.7 per cent.