How much, and when?

Debt Management Office report D8B: gilts in market hands, nominal £ million, by financial year (April to March). This is not who owns the debt. It is when it has to be repaid or refinanced.

The Bank's share of each year's conventional gilts

The only holder the public data splits by maturity is the Bank of England. The purple portion is the nominal amount of conventional gilts in the Asset Purchase Facility that mature in that financial year. The grey is everyone else. Pension funds, banks and overseas investors are not published by maturity, so they stay inside the grey.

A long maturity means less of the stock has to be rolled over at whatever yield is going that year. The UK still borrows for longer than most rich countries. The average has been shortening, which means more of the interest bill resets when yields move.