Looks like he was never promoted to the full rank of S/Ldr.
Last mention is in April 1945 still as F/Lt
http://digital.nls.uk/british-milita...chive/96462666
He has left the service by the next AFL of July 1945
By the way the quickest way to use the ALF to trace someone is go in year steps, look at the back of each AFL for the name in the index to get their personal number and column mentioned. Then look for the entry in the column.
You can check the AFL dates and look for acting ranks by using personal number and last name in a Google search for gazette entry.
Ross