A model tug 'Lady Marianne' sails across Ruislip Reservoir on its own.
Various shots of a model tug 'Lady Marianne' in the Ruislip Reservoir. Several shots of the model engineer Mr Emery (sp?) checking the model engine and pouring paraffin into it. He increases boiler pressure by using bicycle pump. More shots of the tug sailing through water. Mr Emery follows it in a small boat - his two children are in the boat with him.