Vessel moored in the river Colne at Brightlingsea.
From the web these articles came to light.

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HMS MFV 1502 (MFV 1502)
Motor Fishing Vessel of the MFV 1501 class
Navy The Royal Navy
Type Motor Fishing Vessel
Class MFV 1501
Pennant MFV 1502
Built by Richards Ironworks Ltd. (Lowestoft, England, U.K.)
Ordered 27 Nov 1942
Laid down
Launched
Commissioned 14 Jan 1944

https://www.shipsnostalgia.com/showthread.php?t=39069#/topics/39069

https://www.shipphotos.co.uk/ship/?ship=yarmouthnavigator

https://www.nationalhistoricships.org.uk/register/1384/navigator

https://issuu.com/navynews/docs/200103/26