The UK maybe one of the leaders in its acceptance for online gambling, but that doesn't stop the government on trying to clampdown on illegal behaviour – every so often.
Whilst its not illegal for offshore online casinos to advertise in the UK (in the press and outdoor), it is illegal to offer inducements to players – so all those "Get �100 free when you play" or "Sign up and we'll give you �50 free" advertisements are essentially a big no-no on your london cabs.
However, it seems some online gambling companies have been flouting the law – and now the government, together with the newly formed gambling commission, are targeting advertisers that break this law – threatening fines of up to �5000 or 2 years imprisonment
Its always been against the law to offer inducements to players. In fact, most decent online casino companies ensure their ads go through their legal department before going to press. However, there's always those out there that try to slip through. Online casinos are fortunate in being allowed to advertise in the first place – their land-based counterparts are not allowed to advertise at all. As far as I can tell, the online guys should remain firmly on the government's good side, before they lose their opportunity to advertise anywhere
Article: Clampdown on internet casino ads