He is still around in the 1911 census, still at the same address as 1901 which is Litcham Street, St. Pancras
There is this death which could be him although age slightly out.
Deaths Jun 1915
Tompkins John 66 Pancras 1b 164
This gives a birth year of 1849. John's birth year is 1852 however on one census it is given as 1855. The person registering the death may not have known his exact birth year. You can get a pdf from the GRO at a cost of £7.