Ian Lawther

I am new to this forum and have just registered after a friend alerted me to the completion of the Wheatstone Ledgers on line. I have spent the last hour or so look for my concertina in the ledgers, and whilst I have found the numbers immediately before nd after it have failed to find my own...4123. Does anyone have any tips on how to locate something in the ledgers, or background on how the numbering systems worked...it seems to be gradually going up but not in strict order but then throws in things totally out of sequence. Were there a number of parallel series which covered different models perhaps. Thanks, Ian Lawther