Yes! I think you have William's baptism date.
James and Agnes Allan(also Alson) had at least 4 children all born in Dumfries.They are
William b.15/4/1811,Ag labourer and then gamekeeper,blinded by gun shot.Died Moniaive,buried at Glencairn church yard
Jannet b.12/2 1816
William is my 2x greatgrandfather
I am now looking for the births of Agnes and James.