OK, ta J, I'll give it a go.
Also I've just realised the message is decrypted at the 24th pass.
Cheers!
Hurraaaaay! My pleasure, I am glad you worked through this to the bitter end! Now on to new challenges ;)
I'm still trying to figure out the putting spaces in where they exist in the ciphertext, but everything else is now working!
thanks J, your help was very much appreciated.