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