Yes in Sinfin Lane.I ended up working in RR Sinfin A site down the road.
According to the internet QDF as it was 2003 was restructured and ceased cylinder head casting production for tractors and the like around this date.

Qualcast, later QDF Components (Qualcast Derby Foundries) made iron castings for just about any car on U.K. roads up until around 2006, when they were asset-stripped and shut down, despite still being a viable concern. There were patterns dating back to the 30s there at the time,which would have included the original patterns for cars such as the Austin Seven. I can't think of many companies they didn't do work for at some point; even the brake discs for the DeLorean were made by Qualcast, though we were never paid for them The drawings would been in the drawing office also, but sadly all this would have been skipped upon demolition.

When I was there it was mostly automobile parts; but there used to be irons, signs, mowers, drills, grenades, mortars...

We had a Qualcast push-type mower back in the 1950's, and I have seen the name on other things as well, possibly Armstrong Siddeley (Girling) brake drums. So, Ian, your comment about "everyone else on the planet" is probably valid!
Ivan

Location: Wellington, NZ