2 letter UK domains

[rking100uk]

Why is it that the general public cannot buy 2 letter domain name(i.e. ab.co.uk, ac.co.uk) Yet o2 can get o2.co.uk?!?
Has anyone ever mangaged to get one?
Cheers

 

[chs]

You can only purchase letter-number number-letter combinations (e.g. o2.co.uk, 1a.co.uk etc.). I've got three such combinations and others on this board have more.

In the early days you could reg two letters, bt.co.uk is one example, but that is no longer the case.