The RAF’s Bulldogs always had a reputation for being tricky with regard to spin recovery. During my time instructing on them I did a little research into weight and balance, which wasn’t routinely calculated in detail for every flight. It appeared that with two average to heavy occupants the fuel level needed to be watched because many airframes were right on the aft C of G limit and they could be put outside. Which of course might explain the very rapid roll rate that could be experienced. Being built like racing snake back then had its advantage.