Luton use to be EGLN, linked by AFTN to Heathrow. Then the Croydon Communications Centre opened (EGGG) so Luton became EGGW. I went to Croydon CC in the early 70s; it was full of, er, teleprinters . . . . .
Similarly Elstree use to be EGLE and became EGTR.
It always amuses me hearing people complain about codes. Use 'em, you'll soon learn 'em.
Like METAR 'Why can't METARs be in plain language?' I thought they already were!
Anoraks R Us