I had a run through the Northumberland Fusilier service records and it looks like they may have started again instead of using five digit numbers:
8000    June 1901
9284    July 1903
390      Feb 1904
440       Feb 1904
548        March 1904
1182     April 1905
1533     August 1905
By the way, 390 and 1533 both served in India 1906 to 1913.
Phil