Interesting radiator Robert, the direction of the lower water branch manifold suggests it was fitted to a supercharged engine. Not many people seem to know that there's a museum on the Isle of Wight dedicated to Harry Ferguson. It's on a farm owned by his grandson but only open to groups by appointment. One surprise (as my visit was a few years ago) was Ferguson's connection to Austin 7s and there are quite a few photos of him racing his super sports in the Ulster Tourist Trophy along with other famous drivers of that time.

Location: Ferring, West Sussex.

I have a 1930 RK ,106000ish chassis number and that has an A film core.

Many radiator companies when recoring or repairing a radiator would be proud enough to fit a little plate with their company details on it. That would be an interesting point to check as it is nearly always on the header tank.

Location: Deepest darkest Kent

From your photo Robert it appears to have an oval plate on the header tank?
Just looked in Wyatt's book plate 35 showing a late '29 saloon,it's not very clear but I think it's an A film rad.

Austin Harris' site is an excellent source of photos when the cars were new...

It may be worth remembering that Longbridge was a production line of considerable size. Parts will have been sourced from multiple suppliers and any changeover will have spongy edges. You only have to stand by your Sept '28 Chummy at an aniversary rally for about 10 minuites before so called experts start pointing out that you have used the wrong bits in the restoration. My mum got pretty fed up pointing out that she KNOWS that her car was originally supplied with a mag engine, flat doors, un coupled brakes and a 29/30 radiator! W