Cheers folks and I reckon I have found a mother's maiden name.
A few things though - the first might be a technical hitch. I've got three account numbers - 2 for my ancestor's husband made in 1859 and 1862. Then I've got my ancestor's one in 1867. The thing is when I do an exact search on these numbers it shows over 18,000 results - I would have thought either none at all, a couple if they existed but not that many.
The second thing is do the Deposit Account Ledger records only go up to the first 18,000 account numbers. I need to start at 20081.