I think they are referring to:

> Durham University improved by 30 places year-on-year in its students’ evaluation of teaching quality, which was the main driver in securing its third place in the overall university league table

Which isn't quite the same as 30 places in ranking as OP suggests, however I agree with their point that moving 30 places on that metric could be fairly suspicious.

For example - when I was at university in the UK we got a speech telling us basically that we were going to get sent a survey from the times, and the higher we ranked the university, the higher the universities ranking would be, and that would make our degree more valuable. If the main reason they jumped from 7th to 3rd could be a metric that is potentially 'influence-able' by the university, it could be more of a change in comms-strategy than actual university quality.

Appreciate the clarification and perspective.