This photo: https://www.airport-data.com/aircraft/photo/000832649.html

illustrates a classic mistake with citing c/ns for UK-built Chipmunks.

Two discrete serials are used for each aircraft, one being the centre fuselage (hence physical airframe) no., the other being purely a filing number (which will not be found anywhere on the aircraft).

C-GVME is cited as having the c/n C1/0539.

Firstly, file no.s are conventionally cited as 'C1-', not 'C1/'.

Secondly, the fuselage no. has been crossed with the file number.

The correct file no. is C1-0678 and the fuselage no. should be DHB.f.539 ('DH' is obvious, 'B' is the Broughton production line, as opposed to 'H' for the Hatfield line, '.f.' is for a fuselage part, and then a production serial number.

AND there is no sequential relationship between the fuselage number and the filing number.

This last point is the root of confusion which arises over how many British Chipmunks were built. The answer is 'an exact one thousand', but the disconnect between fuselage and filing references explains why the last C1- issued was 1014. Fourteen ordered Chipmjunks were cancelled but only after a C1-xxxx had been allocated to them, and those references were never recovered/reused. However (to further confuse and make the point) C1-1000 was saved for the genuinely last UK Chippie, produced on the Broughton line. It was switched with the aircraft which was have been assigned the file number in sequence but which ended up as the subject of the C1-1014 filing ref.!

If you're not confused yet, I could have a go at explaining Canadian Chipmunk production serials. Any takers? The Portuguese Chipmunk contructor numbers also have their own little twist as well.