Realising that I had not seen much work by Farshid Moussavi, a recently elected RA, I called in at the shop she has designed for Victoria Beckham in Dover Street.   The doorman looked rightly suspicious as he rolled back the door for me, but it has an intriguing use of a grand sculptural staircase stretching up to the first floor and down to the basement, like the one that Koolhaas did for Prada in New York, together with an angular cross geometry which is extended into the seating.   The crossover between fashion and art gallery moves one step closer, not least with a Damien Hirst displayed alongside the clothes.