This is a Momentous Operational milestone.
The pilot was A.W. 'Bill' Bedford. The first tethered hover flight had been made on 21 October of the same year.
Hawker Siddeley subsequently became BAe and the P.1127 evolved into the XV-6A Kestrel and the Harrier (in UK, Spain, Thailand and US service)
A history of the design and development of the P.1127 is given in the Wikipedia entry.