On
http://www.801492.org/Air%20Crew/Downloads.htm, there are two files on Leuchars Ball Project. In the first one (Log, Excel format), you can find:
_ line 108
IDA II 20-sept-44 2J 6C 3P ID 69d 38' N 29d 42' E Successful drop - 1 KIA & A/C 654 lost
_ line 121
654 41-28654 ex-453rd 'Consolidated Mess' Lost 20 Sep 44
https://www.harringtonmuseum.org.uk/...Operations.pdf provides no serial but puts the loss on night of 19-20 September 1944.
The morning report (your link) says the crew departed on 20 September and Allen died on 21st, same date as on his grave, so the date of 19-20 is probably false.