The list of Manchester Regiment PoWs at The National Archives records him as a colour sergeant and has his address as the Riviera Hotel, Margate (I think - the record is very hard to read - see below).
Also it seems to show that he left Changi on 27 October 1942 - this would be with the main group that went to Thailand to work on the Burma Railway (see History of The Manchester Regiment by Lt Cdr A C Bell).
The only confusing bit is that it would normally say "OVL" which stands for "overland", but Dow's entry has "OVS" which I thought stood for "overseas" - so he may have been with another group of PoWs.
Bob B