the grass may be hair grass, Eleocharis acicularis, the other maybe green rush, Juncus ensifolius.

Thanks Sean...

Looking up "hair grass, Eleocharis acicularis" it certainly looks like that is the stuff. I see that it is commonly used as a submerged oxygenator. DOH! Well, regardless of that, it seems happy to grow with just an inch or two of water over the soil and the leaves in the air. But maybe I will see how it likes being submerged - I guess it's more likely to survive the Winter like that. (I see it's supposed to be hardy).

Looking up "green rush, Juncus ensifolius" I think you're right again. By the way, I said the flowers were "red" but I didn't mean scarlet or anything. They were more like dark ruddy brown (which counts as "red" to me :-D) and matches the descriptions I see on the net.

If the back one flowers could it be a sysrinchum?

dampflippers, thanks. But I looked up sysrinchium and it doesn't look like as good a match as Sean's suggestion. In particular I couldn't see a variety that had the same colour and type of flowers. (sysunchium seems to have bigger flowers).