Sanity check on 6.78% 20-year fixed mortgage quote

I’m comparing mortgage quotes for a villa purchase in London at around £608,400. One lender has quoted 6.78% fixed for 20 years. Its advertised rate looked lower, but the arrangement fee and our loan-to-value tier changed the actual offer.

What figure would you prioritise: APR, interest paid during the fixed period, or total cash paid including fees? We may move before the fix ends, so I’m also looking closely at portability and early-repayment terms rather than assuming we will keep it for all 20 years.

I’d compare each offer over the period you realistically expect to keep the mortgage, including fees and any plausible early-repayment charge. Also compare the outstanding balance at the end of that period; cash paid alone can be misleading because some of it reduces principal. APR is useful as a common reference, but it may not reflect your likely moving date.

What is the actual loan-to-value, how large is the arrangement fee, and when do you think a move is most likely? Without those three details, it’s difficult to tell whether the lower advertised rate was ever relevant to your application or whether paying extra for a long fix makes sense.

The uncertain moving date is the detail that changes the comparison for me. If the move never happens, the 20-year fix removes rate-reset risk for a long period; if it happens early, fees, repayment charges and portability conditions may dominate the benefit.

I would first test whether the payment at 6.78% stays manageable if household finances become less favourable. That is the consequence you cannot easily reverse after committing. Then run separate moving dates rather than choosing one expected date and building the whole decision around it. For each date, compare cash paid, remaining balance, arrangement fees and any early-repayment cost. Portability can then be assessed as a possible route, not assumed to solve the early-move case.

Portability deserves its own written comparison; the word alone does not mean every future move will work smoothly under the same terms. Ask each lender what happens if the replacement property, loan amount, or timing changes. A simple table with monthly payment, upfront fee, balance after several possible moving dates, and applicable early-repayment cost should make the trade-off much clearer.