All answers are recognisable pairs 19) Inventor and dog not always a walk in the park (7 & 6) 28)Ralph and Leslie's company in Wigmore Street (6&6) 50)79 and 47 found solidly in table for scientists (4&6) 51)Young men with partners literally (4&6) 55)Terry Pratchett novel fit for any gentlemen (5&6)