Where in the UK is a phone number beginning 020 8888?

Where in the UK is a phone number beginning 020 8888?
If this is a LONDON, UK, number then the correct format for the number is:

(020) 8888 xxxx

The area served by 8888 is WOOD GREEN.

These numbers were previously in the 0181-888-xxxx block, and before that in the 081-888-xxxx, block.

Way before that they were originally in the 01-888-xxxx block, pre 1990.