Mobile Today has a neat graphic for subscriber takeup in the UK:

However, where is 3? As Ed Cross says:

What it looks really interesting is the total cumulative amount of subscribers in the study to be 66.7 million, this number does not consider "3", lets add maybe another 5 million for their probable share?, Tesco Mobile, Dot Mobile, and any other MVNO's i am not aware of (EasyMobile closed last december), lets add 1 million for these group?. So the total approximate number of UK subscribers maybe is set at around 73 Million, big wow! This is what i call real market penetration.