If inflation is 2.5% avg, then you need to get a job at B&Q at age 78.
With inflation alone, that 28,700 pension will be sucking 75k when you are 80, from your pot.
Depends what you're invested in.
Obv. cash, bonds, fixed interest will shrivel up, but asset-backed securities (e,g. National Grid, Marks and Spencer, Wetherspoons, Glaxo) will tend to keep pace. As you never know which will be the successful businesses, and which will collapse, a low-cost tracker is supposed to keep pace with the market even if you have no interest in investment.
Funnily enough, my late grandad invested in FW Woolworth many years ago, which you'll remember collapsed, although when he bought it, it was viewed as rock solid. However his young widow made a fortune out of Kingfisher, which was split off from Wooworths,, and spawned B&Q and
Screwfix, even though she took no action. So you never know.
I am personally very much prejudiced against cash, bonds and fixed interest for long term investment, even though a bit is considered a short-term safety net against market crashes.