I think it depends on wash and cut.
My lavenders are madrid cut.. other ppl have said they run big enough to size down, but they fit me fine. Maybe because these are a newer line? I find they run quite tts. But I know this wash (vapor) stretch out loads after wear.. but I think if you get your correct size then and pop them in the dryer every now and then they'll shrink back
The R's did look big on you... I think madrid's are similar to roth cut? I don't know someone correct me. So mayb you are actually a size 26... and not 27/28! In general I find RR jeans run bigger.
if you're gettin londons.. those run smaller. I have a pair of 25 fuschias and they fit me ok.. with abit of hot dryer work that is.