Soon the inevitable happened. Bill Roberts was approached by Pinewood Studios for model aircraft to feature in the air epic of World War II, Angels 15, starring John Gregson. Then came the Phyllis Calvert film, The Net, and this led to Bill Roberts' biggest job so far : a full-scale "mock-up" of a Vickers Vimy aircraft for the film, The Long Hop.
"It had a 67' wingspan," says Bill, "and stood taller than a double-decker bus. We installed two engines which allowed it to taxi realistically at 20 miles an hour. That was quite a job, we only had a shack at Iver, Bucks, at that time - we moved here much later - and it was too small to house even the parts successfully.
"So we built the aircraft in a field outside. It had to be tied down in sections in case it blew away. We spent what little spare time we had praying for good calm weather."
Then came a 40' model of the ill-fated Titanic for the Kenneth More movie, A Night to Remember, followed by a commission for 180 model planes varying in size from very small to 5' wingspan for another More film, the Bader story, Reach - for the Sky.
"That was a tricky one," says Roberts. "We spent three days crashing one model effectively - the aircraft that was supposed to cost Kenny his legs "
One piece of aircraft mechanism has never presented any problems to Bill Roberts. Propellers. He worked for some years as a prop-shaper at the famous Airscrew factory at Weybridge, Surrey.
Then came the ship period. Roberts made battleships and cruisers for films like Sink the Bismarck, and models up to 33' in length for Battle of the River Plate, in which the star model was the Nazi ship Graf Spee.
Following the American trade showing of Sink the Bismarck, the American distributors remarked about how the "stockshots" - old newsreels - gave the movie a feeling of authenticity. In fact, of course, there were no "stockshots" : they were all Shawcraft models filmed in a tank !
An astute man, Bill Roberts was not content to make models just for the movie industry. He became familiar with the general workings of a studio and quietly produced an automatic film processing machine, some 40' long, capable of dealing with 300 colour films an hour.
The Rank Organisation commissioned three such machines which are still in daily use.
Fibreglass and steel tanks of any size for the treatment of metals, for film processing, industrial models of all types, educational aids; Bill Roberts makes them all in his smallish, overcrowded workshops.
But it is the show-business side of his production which is the most amazing. No Dr. Who programme would be complete without a Shawcraft contribution. Perhaps the most famous of all the Who monsters were - and are - the Daleks.
Dreamed up by writer Terry Nation and designed by Raymond Cusick of the BBC Design Team, they were the first "monsters" in the Shawcraft library. They were followed by the Zarbies - ant-like creatures, actually articulated suits worn by actors - and the more lovable Chumbleys.
"Working" instrument panels for space travel, upon which lights flash and dials register electronically, are just part of Shawcraft's weekly chore.
Rockets of intriguing complexity, launching-pads, a scale model of the city of Troy - you name it, and you will find it in Bill's workshops. Everything from a pterodactyl to a drinks machine and accompanying chair for the BBC play Out of the Unknown.
"Actually, there is a man inside the drinks machine," says Bill. "It's cheaper that way. The idea is this mastermind sits in a hydraulically operated chair, which turns to a lounging couch at a touch, and the drinks machine obeys his commands, spilling whisky, gin or vodka into a glass, adding ice and cordial and even using a swizzle stick before passing it."
A series of spouts dispenses the "liquor," there is a chute for ice, and the "swizzle stick" operates on a complicated mechanical arm.
Here, as in everything else, Roberts' keen attention to detail is evident. Detail and finish. The finish on every product is impeccable. Shawcraft models are obviously made to last.
What of the future?
"Well, I seem to have so many irons in the fire, I just cannot predict which way things will go," says Bill. "But one thing is certain. While there is a demand for monsters, whether they be from outer space or under the sea, they will be born at Shawcraft."
And next Saturday and every Saturday after, the small boys and the bigger boys, and even the fathers, will be glancing into the cluttered yard on the busy Slough Road, hoping to get a preview of what their home screen will show them.
But security measures are strict: all the passersby can see are the familiar monsters of the past the Daleks, the Zarbies, and maybe a Chumbley.