I have a little spreadsheet that shows the erosion over time of pension value as payment increases fall behind inflation. Its quite easy to build your own, but if anyone wants a copy, do ask (making the obvious amendment to my email address).
For example, if one assumes inflation is comparatively benign 2.5% and pension increases are 70% of inflation, then over 30 years the "real value" of one's pension falls to 81% of its original purchasing power. If inflation is 5%, the fall is to 66%, and - perish the thought - at 7.5% inflation it would fall to 54%.
And to make it worse, as others have noted in this forum, the elderly have greater need of higher inflation services such as medical insurance and care fees, which are not balanced by their possibly lower interest in lower inflation manufactured goods.