Anyone here from Bletchley Park? ?

I haven't studied the letters but at first glance I wondered if it could be a 'word search'. But it may simply be random letters. Where I live there are hundreds of painted stones in tribute to the NHS.

There’s a thought Monica- back to the drawing board!

t has clearly been made very recently, ie this summer or possibly only a day or so before it was discovered as the letters are so bright and clear.

More than 24 hours in the sea or rolling round the beach and if all signs of writing had not disappeared they would be pale and illegible.

As the letters are in rainbow colours are the letters the first letters of words making out aa tribute to the NHS?

I wonder whether the colours are significant?

I've looked at it, Katek and so far I have worked out that it isn't a substitution code - none of the ones I suggested - because all the letters are fairly common ones, and the ones not represented (JKBF etc) are uncommon ones. (If you are substituting one letter of the alphabet for another, you always end up with some of the uncommon ones.) So IF it really is in code, all the letters of the original message are there in the coded version, mixed up somehow. The trick is to work out what pattern was used to mix them!

Could it be a BristolRock, stones decorated and left for people to find and place elsewhere or just keep?

Thank you Elegran! Let the head scratching and pencil chewing begin!

Now is your chance to introduce him to the challenge of simple cyphers! Start with the reversed alphabet A=Z, B=Y etc, then if that doesn't work, the move-on-a-letter one (B instead of A, C instead of B etc) followed by the move-back-a letter and the move-on-two-letters and so on. If he gets hooked, there are plenty of websites with more advanced cyphers.
Good luck!