Hugz wrote: There may be a W in front of your number that is a bit faint.
aha!! I'm in awe of your knowledge, I took a photograph of the serial number which no 'W' is visible at all on, I just went back and had another look at the engine and there is indeed a very very faint 'W' the full serial is infact
WSPCL1517FF6 which clears up my confusion,
The engine has unfortunately been 'improved' with blue paint

so it's not the easiest thing in the world currently to tell what is meant to be what colour, I'm intending on cleaning the engine down a bit to restore some of it's original looks where possible, but that's something to do over the spring.
Thanks again