Confidence: It might be this.
Notes: New season shoots of an aquatic emergent with a strikingly pink colour. Presumably leaves will start to produce chlorophyll in a short while? There was old growth of Typha reedmace nearby so this could be that I suppose but I would have expected green regrowth amongst the old typha stems which was not the case. These plant were growing in open (not deep) water some way from the edge of the Typha stand. Of course I could wait and see what they mature into but I would be pleased if anyone can give me a hint in the meantime!