Yes it's a Marathon. I only met one navigator who'd received training in a Marathon and he wasn't very complimentary about it. Slow and with a very poor rate of climb (30 min to 15000ft if light enough) and they often bumped around at 5-7000 ft in and out of cloud.
There was a nasty fatal accident following probable loss of control leading to an overstress - it was later established thet the stick force per 'g' at high speed was much lighter than the RAF requirement.
All yours Noyade