I'm after the ants not the plant
I was wondering if it might be some kind of more specialist ant given that this is a water plant so ant might have to risk life and limb to get to nectar
The two-part petiole and propodeal spines exclude all Lasius and any other Formicine ant. The scape indicates either M. rubra or M. ruginodis, but the crucial bits are not shown clearly (though from what we can see of the spines, I think the former).
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
Have added the only other photo i have, not sure this is any more helpful.
I would not stake my life on it, Mike, but the new pic points more strongly to M. rubra. The spines seem too short for ruginodis, and it is certainly one or other.
Lat/Lng: 51.07985, -0.33299
OS grid ref: TQ168324
Can't remember exact location but its certainly at warnham nature reserve which is quite small and i only went to a small part of it so error would be max 50-100metres.