@Pillypocket666
Because he may be innocent?
Legally speaking, he is of course presumed innocent until/unless proven guilty. (And rightly so - abhorrent as the low rate of conviction in rape cases is, throwing out the principle that innocence is presumed rather than guilt would utterly undermine our justice system).
However, anonymity is different. There is no right for defendants to remain anonymous as a general rule. This is for a number of reasons.
(1) The presumption in this country is that justice should be seen to be done in public to ensure everyone's right to a fair trial. (In fact, the one area which has abandoned this - the family courst - is the one with the biggest question marks over it in terms of fairness.)
(2) It gives a chance for other victims to come forward (e.g. the Worboys case).
(3) By the same token, it can also help the accused, if for instance, someone sees his name in the paper and thinks "but he was with me the night this is meant to have happened" and comes forward with an alibi.
I suspect the reason his name is being withheld is because in this instance it would uniquely identify the woman who brought the accusation (and victims are given anonymity in rape trials).