Officers received report of a man visiting an 82-year-old woman in Escots Drive about 2.30pm on 26 October claiming to be from the water board.
After being allowed into the property a quantity of cash and cards were stolen from the victim.
The suspect is described as a white male with a slight tan, 5’8”, of a stocky build, aged around 40. He spoke with a London accent and was dressed in all black clothing and a black beanie style hat.
Police are keen to speak to anyone who saw any suspicious vehicles or persons seen in or around this area of East Grinstead between midday and 3pm.
Anyone with information can report online or call 101, quoting 820 of 26/10.