What if those people are still benefiting from other people's sins? If the current British don't want to pay maybe they can dispose of the ill-gotten gains i.e the country estates paid for by black slaves, the textile fortunes paid for by exploited Indian cotton farmers, the Kohinoor diamond in the Crown jewels etc.

Well it was clear from WW2 records that British were not willing to pay India even for the support India gave to them during the war. They only relented in the face of American pressure. Records also show that much of the 'development' in India such as railways was made practicable by Indian capital and labor, while the rewards of it all went directly to finance the Industrial Revolution in the west. The 'why' of this mindset of take-take only became clear to me when I followed events after the British losses of American colonies.

When any side feels the dominant emotion of 'loss', it makes it do selfish things to avoid future losses. But that extracts more losses from the other side and so the cycle can continue.

In the light of all that history, which current Indians being on the receiving side remember more than the British, any help the British give to India is at least perceived by India in a positive way.

As to the extent of the monetary help - its effect is limited by the ability of the recipient to absorb it. For analogy, YC reduced the investment into each startup down from $150k as it made things worse, not better.