The government are using Pension credit as the way to determine eligibility.
People can only get pension credit if they have no personal pensions and only have the state pension to rely on.
Someone on pension credit would get £11,343.80 per year, plus the winter fuel allowance (£200).
Someone who has a small private pension of £1,000 per year would get about £12500 per year in total but no fuel allowance.
The point is that there isn't much difference between these two. But how else does the government differentiate these pensioners from the millionaire pensioners?
I liked the suggestion to make the payment taxable, so that high earning pensioners at least have some clawed back by the government.