this is from wikipedia:
As Wilson wished to remain an MP after leaving office, he was not immediately given the peerage customarily offered to retired Prime Ministers, but instead was created a Knight of the Garter. On leaving the House of Commons after the 1983 general election he was created Baron Wilson of Rievaulx, after Rievaulx Abbey, in the north of his native Yorkshire.
knighthoods don't get passed down. Peerages may be, it depends: life peers don't pass on their titles. Thatcher was made a baroness and her husbadn was given a baronetcy, which their entirely disreputable son Mark has now inherited.