Source: Leicestershire War Memorials Project.
Market Harborough Advertiser, October 1st 1943:

'Market Harborough Naval Gunner Missing'
Mr Tom Smith of 20 Hillside Road. Market Harborough has received an intimation that his nephew, Gunner John B Smith RA, was on board the SS Lisbon Maru when that vessel was sunk and must be regarded as missing at sea.
Gunner Smith is the son of the late Mr and Mrs Harry Smith. He has two married sisters living in the town.'

Market Harborough Advertiser, 6th October 1944:
' Market Harborough Gunner Killed in Action'

' Mr TB Smith of 20 Hillside Road, Market Harborough, has received a letter from the War Office to the effect that his nephew, Gunner J. Brazier Smith, RA, is now presumed to have been killed in action. Gunner Smith was reported 'missing at sea' in September, 1943. The War Office now write: 'After careful review of the available evidence the Department has reached the conclusion that all hope of his survival must be abandoned and that there can no longer be any alternative but to presume that your nephew must have been lost when the ship on which he was being conveyed as a Prisoner of War from Hong Kong to Japan was sunk. It is therefore proposed to record officially that Gunner JB Smith is presumed to have been killed in action at sea while a prisoner of war in October 1942.'
'Gunner Smith was the only son of the late Mr and Mrs Harry Smith, well known residents of Market Harborough. Two married sisters of his reside at Market Harborough'.
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Kindly submitted by B. Hakewill, 2018.

The CWGC website records a Gunner J Smith 847789 of the 7Bty 5 AA Regiment, RA, who died between 1-2nd October 1942.

This is the date of the sinking of the Lisbon Maru, a cargo ship used for the transfer of POWs, notorious for its appalling conditions onboard. The Lisbon Maru was torpedoed by USS Grouper on 1st October 1942 and sank the following day. 800 POWs were lost at sea during the incident, many thought to have been shot or otherwise killed by the ship's guards.