The offenders entered a field at the rear of the property, removing gate hinges and taking down wooden fence posts and barbed wire.
They then stole a traditional gypsy style caravan which is valued at £20,000.
The caravan is described as 14 to 15 feet tall, maroon in colour with hand painted panels in green, red and gold. It has large yellow wheels with red trim and a yellow box to the rear which was once used for carrying coal. The roof is painted pale yellow.
PC Annelisa Cass, said: “This caravan is of huge sentimental value to the elderly victims who have owned it for 30 years."
Anyone with information should contact PC Cass at North Walls police station on 101