The Civil Aircraft Register currently shows 16003 entries. May or not be up-to-date, after all it is CAsA.
Showing 1 - 30 of 16003 results.
Total number of unique combinations of three letter combinations.
26 x 26 x 26 = 17576.
= 1573 available registrations?
17576 divided by 10 per week = 157 weeks = 3 years.