The debts consolidated read like a history of the UK including costs from Napoleonic wars and even the South Sea Bubble Crisis of 1720.
Now, the UK government has now announced that it will begin "calling" - or redeeming - some of these debts - in effect finally paying them off.
Consols are interesting not just because of the slice of history that they provide, but because they are also perpetual bonds. The pay a fixed coupon forever. They are valued using the simple formula:
A recent quote shows a 2.5% consol trading off a yield of about 3.86%. This would price the bond at:
The Economist has a nice article about the introduction of Consols. (Might be behind a paywall).
As a side, from this picture of one of the bonds that was consolidated. It is pretty clear why we call interest payments on debts "coupons"!
Perpetual securities are actually not as rare as we might think. Another similar type of security is Preferred Stock - which pays a fixed dividend forever. Berkshire Hathaway (Warren Buffet's firm) bought a big chunk of preferred stock from Bank of America a few years back.