Just to thank the group for the suggestion that changing the hand brake switch may cure the problem of the 'brake fluid warning message' appearing for no apparent reason.
Obviously, I first checked the fluid level itself which was fine. I then presumed a problem with the fluid level switch, disconnected it/shorted it, which again had no effect.
Fortunately, I then looked on the forum, which suggested the hand brake switch change. Like everyone else, I was skeptical and couldnt see the relationship, but for the sake of a ten minute job and =A32.65 from the local Peugeot Dealer I gave it a try....Problem Solved!!!
Prior to changing the switch I had wondered whether the computer was looking at different resistances in the message circuits and somehow the brake switch had developed a high resistance which was triggering the faulty message. On changing the switch, I did indeed measure a high resistance across the switch while in its 'open' condition which seems to go along with my presumption of how the computer reads its message circuits.
By the way, when I went to purchase the switch and explained why I was replacing it, the dealer went to great lengths to explain I was changing the 'wrong' switch.Fortunately this advise was ignored...........THANKS AGAIN TO THE GROUP