Now that's kinda bull right there! You're considered employed if you get paid the equivalent of minimum wage for one hour's worth of work. I've rarely heard anything so stupid about labor laws ever aside from areas that don't have any.
The British car industry collapsed because of, in a space of time from 1968-2005, British Leyland/Austin-Rover/Rover being mismanaged and having constant strikes, being semi-nationalized, being privatized and sold to BMW who only wanted the Mini brand as their own, and now MG-Rover is owned by a Chinese conglomerate.
That all being said, Ford, GM (Vauxhall), Nissan, Honda and Toyota build cars in the UK, most F1 teams are based in the UK, XTrac builds most of the gearboxes used in F1 and sportscar racing and rallying, and the Williams F1 team builds the flywheel hybrid system used in the variants of the Audi R18 e-tron quattro that have raced at Le Mans since 2012. Also, Ricardo builds parts for the Bugatti Veyron and though owned by Volkswagen Group and BMW, Bentley and Rolls-Royce still build their cars in the UK, and Aston Martin is now majority British owned by a consortium lead by Prodrive founder/owner David Richards, in conjunction with Ford, who still own 12% of Aston Martin.
They still build cars and such in Britain, though a lot of the companies are under foreign ownership.
As for the deal with Australia, I know that Ford wanted to kill the Falcon, and that it was them wanting to stop manufacture there that would do it. It would be replaced with the Mondeo (EU/UK version of the NA Fusion) and a RHD version of the Ford Mustang. The Holden Commodore is sold in the US as the Chevy SS, and the Buick Park Avenue is sold and built in China based off the Commodore's chassis. So that killed the Australian built Commodore. And Toyota sell a similar line up in Australia as they do in Europe and NA, so that killed Australian production.
The problem is economics and that it's cheaper to import similar cars into the area than build them there.