An amount of £15,000 in 1960 would be worth approximately £448,417.50 in 2026.
I’ve just googled the worth of £15k in today’s money. One of the problems is you want to tax inflation.
At the moment, people are allowed to make a property gain on one property - most people don’t own more than one house. If the gain on property was taxed on sale, people probably wouldn’t be able to move house.
A smallish sized family house should not be deemed a mansion, even if it is worth £2m+. Maybe along with regional spending plans, we should have regional taxation plans. In some parts of the UK we could call houses at £200k mansions. If not why not? Maybe we should tax the amount of land used instead?
I do think IHT should be more widespread - less allowances. CGT needs to allow for inflation and it currently doesn’t. There are lots of anomalies with tax that need sorting out to make taxation fairer. Everyone should pay tax - but it needs to be spread amongst everyone.