Survey reveals huge price mark-up by British retailers

It’s margins that matter, not the prices. How do the margins compare?

I believe almost all of the non-perishables are centrally purchased, therefore same cost price for UK and ROI stores - am I correct in this belief, anyone?

It is not margins that you need. It is cash return on capital employed (CROCE).

Higher margins might be needed to justify higher wage costs, higher rents etc. etc.