Build Number

[709542]

I have spent some three years now transforming a very green,damp and neglected 27 previously known as Pierrot to a boat I am now proud to own. Boat has been re-named Live Wyre and is moored at Bridgehouse Marina on Lancaster Canal.
In the general clearout of the garbage left on board, I dumped a very dilapidated 'tool box' as it was full of rusty and unusable tools. It transpires that the Build Number Plate was in the box, removed by the previous owner when he varnished the cabin door. Having hunted in all the recommended places on the boat to find the number, I have found the number 100 marked in pencil on the wooden support beam just above the petrol tank in the bilge. Could this be the Buld Number? If anyone can help it would be appreciated.
Regards
Richard Sumner