In 2015, he was quoted as saying to the Daily Express: “Many of my scenes were with Jack Warner, who played Dixon – particularly as his right-hand man with a fast pair of legs, whenever we had to chase a load of crooks. The producers allowed me to progress through the ranks to acting sergeant, sergeant and even dog handler.”
Article source: https://www.huffingtonpost.co.uk/entry/grange-hill-actor-nicholas-donnelly-dies-aged-83_uk_61dc4727e4b0c7d8b8b2f8bb