WIth LloydsTSB, they had 2 computer systems running for a number of years (one TSB and one Lloyds), as such the loans taken out during the period before they decided which computer system to use (the TSB one in the end) meant that interest was calculated differently. TSB loans were front loaded with interest, while Lloyds loans were calculated with daily interest and this was applied monthly along with your repayment. Of course over the full term of the loan, the same amount of interest was charged regardless but for early repayment it differers. Was the loan taken out at an old Lloyds or TSB, that would give you a clue.