If you get a day off and you end up spending it doing what you normally do on any working day, then you call it a `busman’s holiday’. Instead of going out and enjoying yourself, you spend the day as if it were any other working day — doing office work. By the way, the `a’ in `man’ is pronounced like the `a’ in `china’.
The expression comes from the time when buses in London were pulled by horses. Every driver was given his own team of horses, and man and animal worked together every day. As it usually happens in such circumstances, a close relationship developed between the driver and his team. Whenever the driver went on leave, a substitute was hired to `drive’ the bus. Very often the regular driver would sit in his bus all day as a passenger just to make sure that his horses were being properly treated by the substitute. Since the driver ended up doing what he normally did on any working day, these rides began to be called `busman’s holiday’.
*I thought I would make it a busman’s holiday and finish writing the report.