Police say the burglary took place between 2.45pm and 5.45pm.
According to police, the offender managed to gain access to the building before forcing entry into the flat while the occupant was out and stole several thousand pounds worth of jewellery which had great sentimental value.
One item was described as a gold locket over 100 years old with a basket of flowers engraved on the front and two lovebirds on the rear, police have said.
Detective Constable Gavin Percival said: “If you saw anything suspicious, know who is responsible or have been offered similar items then do not hesitate to contact me or your local officers.”
Any witness or anyone with information is asked to email [email protected] quoting serial 1031 of 101.
You can also report online to https://sussex.police.uk/contact-us/response-to-appeal/ or call 101 or the independent charity Crimestoppers anonymously on 0800 555 111 (www.crimsetoppers-uk.org).
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