P/O Walter John Lawson 19 Sq Info search

I am trying to find out as much as I can, for a book I am compiling, on the service history of a relative, P/O (later SqLdr) Walter John Lawson.

He was based with 19 sq Fowlmere, I think either from 1939 or 40 onward.
He had some success in combat, shooting down 6 aircraft.

He flew with George Unwin and a number of other well know 19sq pilots.
I am aware that he was present at the Duxford press day 4 May 1939, as I have a still photo taken of him with George Unwin ,Brian Lane, and Bernad Jennings.
Although I recall seeing a clip on TV once I havent been able to find any links to the Press day footage, does it exist anywhere ?

He flew Mk 1 & 11 spitfires, call sign QV-K QV-J and I think QV-I.
I have a photo (although rather small) of him flying in QV-J.

I am aware that he flew X4170 a few days before P/O Oxspring and made a succesful forced landing at Eastchurch.

He was last reported MIA 28 aug 1941 after flying as sq/ldr for a circus over to Rotterdam support Blenheims.
P/O Cunningham was also on that circus and was also shot down crash landing on the Dutch beach-POW.

Apparently a search was carried out following day for Lawson resulting in 4 more losses.

Other than that I can find nothing more.

Any further info about P/O Lawson would be most helpful.

regards
Jon