Thirty years ago, just before midnight on New Year's Eve, Michael Harrison slipped away from his family's party at home in Surrey and was driven to Parliament Square.

There, he made history - by making Britain's first mobile phone call to his father Sir Ernest Harrison, the chairman of a new firm called Racal Vodafone.

Vodafone was one of two firms given a licence to operate a new cellular phone network - and it was in a race to beat its rival BT Cellnet to get up and running first.

It succeeded - Cellnet's first call came a few weeks into 1985.

In an exclusive interview, Michael Harrison recalls that historic moment to BBC technology correspondent Rory Cellan-Jones.