Most distribution Voltages in the UK are 10% higher than nice round numbers.. 11 and 33 kV are widely used, 66 kV for some large substations. 22 kV is not much used in the UK, more common on the mainland, but the London Underground has quite a bit of it, I think because joints in 33 kV were too large.

6.6 kV is still used, though becomming less common. Quite a lot of Croydon is still fed ay that Voltage.