Lance V thanks for all your comments, I have edited the randomised key in the opening post, also to answer your point about the randomisation, the key has been heavily randomised. I did initially start moving blocks of 2 or more characters around before it dawned on me that that was not the wisest method. In the end I made a table, as eluded to earlier, and resorted an adjacent random number column multiple times.
If the concern was completely random. So it is extremely difficult to find the right combination..
We are talking about millions of possibilities. It is not impossible, but it takes a very high processing capacity to be able to do this in a timely manner.
If it was done using logic, then it might be easier. Even so, it would be necessary to first discover this logic, which will be equally difficult.
It is still an interesting challenge.