what happened before the law changed ?
anyway under the 2002 land registration act
it is all electronic
and they previously said "thro them all away"
however now they advise to keep them ( ha!) in case there is a dispute in which they might be of value
the basic rule is that ownership doesn't change
is is just that there is now no building the owner of the land can live in or let.
after the bombing during the war - if the bomb site was rebuilt - then the pre war lease still held sway
( not - new building new lease and the pre war leasholders could sod off )