Finnigan's Waxoyl was my favourite. Tried I think was it Dinitrol, and the one by Plastic Padding? Probably others just as good.No idea who does it in your area, someone into restoration work, who does a good job?
I've just been rustproofing the Coupe and did a bit of research.
What I used was a wire brush on a drill, then I brushed on 2 coats of rust converter (Kurust did well in Practical Classics group test), then I wire brushed it off again and applied Zinc 182 primer- 2 coats, then 2 coats of Hammerite, then Dinitrol RC3125 which is the waxy stuff.
Dinitrol is about 3x the price of Waxoyl so I'd use Waxoyl to rustproof the whole car and Dinitrol to brush into localised areas which have rusted. I won't know how well it's worked for about a year but have had excellent results with the Zinc182 in the past and very poor results from trying to brush Hammerite straight onto wire brushed rusted metal.
The coupe had a leaky waterpump so I've been doing the fabled 20v cambelt job with waterpump. A lot of this is in the wheelarch so I did this at the same time. Here are some before/after photos. The Dinitrol 3125 is brown in colour. I just brushed it on.
I put the 145 on Autotrader and it was gone in 48 hours.