Where a contract involves the performance of a service, it is possible that the service will be provided by a third party to the contract.

In Robson and Sharpe v Drummond (1831) 2 B & Ad 303 a person had agreed to keep a carriage in repair for five years and to paint it from time to time. It was held by the court that he was not entitled to delegate performance of the contract to his partner. This was seen as a contract of personal service and it might neatly be contrasted with British Waggon Co v Lea & Co (1880) 5 QBD 149, where a contract to let out railway wagons and to keep them in repair for seven years could be vicariously performed since it did not matter to the hirer who kept the wagons in repair so long as the work was properly done. Here the judge emphasised that the work was of an ordinary nature which could be accomplished by the average workman.