Spitfire factory numbers

i have a spitfire wreck and im fairly sure of the s/n, but have also found a number scratched in old cursive in letters about 1″ high on the inside of the longeron, its original and has a bit of corrosion through the number but is readable, and was likely done in the factory.

the longeron also has the stamped number 30027 from memory.

does the other number mean anything? is it a build number? its a 5 digit number starting with 2