Mrs R and I also went to this market, we saw Rambling Phil, Juanita, Plum (and Mr Plum and the Plumletts), so with you lot too it looks like the whole of the SE1 forum was there are various times.
We really liked it, even though we'd only gone to check out what was there, without the intention of buying anything. We left with 3 pots of chutney, a litre of draught Severn Cider Perry, and we had a sausage sandwich whilst there. Some of the produce was a lot more expensive than you'd get elsewhere, but you pay for the quality (organic, fresh, free range etc).
We'll certainly go back there, when we want something a bit special (the goat cheeses were fantastic)
I live within spitting distance of the square so popped along. Good array of stalls (not sure if THREE bread stalls were entirely necessary, but they all looked delicious) and although I didn't buy anything this time, I really enjoyed the atmosphere and will certainly visit every week.