Engineering company that was in Willow Lane, Mitcham.
From ads in Wireless World, it may have been trading between 1958 and 1966. The first ad, see below, refers to a cathode ray pumping unit and that the firm were specialists in the design and manufacture of vacuum equipment.

Vacwell Engineering factory building
From the 29th April 1966 issue of Mitcham News & Mercury:
RUSSIAN SCIENTIST KILLED IN BLAST
Four injured and taken to hospital
A RUSSIAN scientist was killed in an explosion at a Mitcham laboratory on Tuesday.
Four other men, one a Russian and three on the staff of the firm were hurt. They were taken to St. Helier Hospital.
The dead man was watching an experiment at the Vacwell put Engineering Company, Willow Lane, when the explosion
occurred.Shortly afterwards a Soviet Trade Delegation went to the factory.
And strict security was imposed at the hospital and factory while the cause of the accident was being investigated.
On Wednesday no one at the factory would comment on the accident. A spokesman said: “We are not taking any Press inquiries.”
But the explosion blasted a hole in the laboratory’s roof – 100 on yards from the main factory building
Later the dead man’s name was given as Victor Stroujinsky. Three of the injured men include 28-vear-old Mr. Ronald Neale, a physicist at the firm, Gassiot Way, Sutton, who received injuries to his left leg, burns and bruises; Mr. P. Rose. of Caterham, a director of the firm, who received cuts, and fire brigade Sub-Officer William Chalk, Lymington Close Norbury, who was overcome by fumes.
Four other Russians who were also watching the experiment were unhurt.
The company, which makes electronic equipment, is believed to be under contract with the Soviet Union. And it is usual for the Russian authorities to attach inspectors to firms producing goods for them.
Dropped ampule
Later on Wednesday police said Mr Stroujinsky was handling ampules of a chemical when he dropped one and broke others which resulted in the explosion.
The following ads are via the Internet Archive Digital Library of Amateur Radio.

From Wireless World, October 1959, via the Internet Archive