13721 is probably an 11th Service Battalion (Lonsdale) number. The date of entry matches and the service record of 13720, Stanley Arnstrong, is on Ancestry.
516139 Labour Corps was issued between October and February 1918.
60895 Lancashire Fusiliers appears to be from a batch of Labour Corps men transferred to 23rd Garrison Battalion, Lancs Fusiliers on 1st June 1918.
Phil
That's just what I did Ady
