Well done Stu…again . Ann , we need little Mart’s working out …no points without it . I got in such a pickles ,I posed the question on The Chiswick Forum ,and this was the explanation…..
The code is alphabet based:
1st letter +1 (B)
2nd letter stays the same (U)
3rd letter -1 (L)
4th letter +2 (B)
The 4th letter restarts the alphabet cycle.
Anyone hear John Bishop on Desert island Discs ? He had some lovely choices , especially the penultimate one , a David Grey song . Quite took the wind out of my sails , it is hard to pull back after that .