One of my most interesting recent cases involved tracing a clients family back from the London suburbs to rural Oxfordshire, and the interesting discovery that my client’s great great great grandfather had been transported to Bermuda for a period of fifteen years for burglary! He did return to the UK after around 8 years.
Finding ancestors with criminal records can always give a great deal of extra detail. For example, the ancestor in question who had been born about 1820, was 5 feet 7 inches tall, of fair complexion with dark brown hair and had a birth mark about an inch long on his left thumb!