"On the question of the 532 and 542 papers: the Silverprint website states that 542 is discontinued(?) and there is no mention of 532. Retro does not list either. Does anyone know where one can get these papers in the UK?"
I noticed that too on the Silverprint site. However, checking other sites in Europe and the US makes me think that it is just 'out of stock', not discontinued (I hope I'm not wrong here! I love the 542 and can't wait to try the 532 once it's in stock again...)