Gordon, could the prefix to the serial number be a "G" rather then a "C"? Brown's London Gunmakers list the following as prefix letters: A, E, G, K, O and T (but no C).
If it is, in fact, a G then this series began at 5001 in 1902 and finished at 6588 in 1939. The date given by MDC above is for the no-prefix series and was mostly used for best guns, the prefix series were used on lesser quality guns.
There should be letters on the proofmarks with the crossed swords (mostly likely a date stamp but there is another use for a similar mark). The crossed axes is most likely the crossed sceptre marks and they have a crown on top and letters as well. If you can more fully describe these marks (photos are best) then it is possible that a more accurate date can be given.
