The building was granted Grade II listed status in 1980, and was in use until the late 1980’s. The factory was built to produce Hoover vacuum cleaners but also manufactured electrical equipment for aircraft and tanks during the war. Whilst part of the original factory is now a Tesco, it would appear that the self contained 'Hoover Building' which faces onto the road, and underwent a full refurbishment in 1997, is still available to anyone in need of the space, as long as they have money to burn.
A website which appears to be touting for potential occupants claims the current rent is £480,000 per annum, but it appears running costs and business rates would set you back another few hundred thousand pounds. Your author thinks its probably beyond his means at this time.
For more, see http://www.hooverbuilding.co.uk/