While searching around for another puzzle to help digest that Xmas dinner, I found this genuine gem.
It seems that GCHQ (British Secret Service) who
specialise in eavesdropping, have opened an entertaining Christmas quiz to attract potential recuits.
Classed as hard, it will take some time to solve.
Still its a unique chance to see how far you get, before you give up?
http://www.gchq.gov.uk/codebreaking/

Some kind of (rolling) substitution comes mind?

[QUOTE
Classed as hard, it will take some time to solve.
Still its a unique chance to see how far you get, before you give up?
http://www.gchq.gov.uk/codebreaking/

Substitution comes mind? [/QB][/QUOTE]

Seems it cant be as hard as I thought it might be.
According to the 'Telegraph' newspaper
yesterday two people have sent in correct answers, so far.