Alex,
Have trawled thru online Singapore newspaper archives with several search criteria but so far no match (either with or without casualties) found with (a) Beaufighter on an anti-mosquito flight.
See
http://eresources.nlb.gov.sg/newspapers/default.aspx
With some browsing, other fine (RAF) details may emerge there, even serendipitously...
Regards,
Leendert