Hi Factor30
Prior to about 2006 if an estate was left to the spouse and then to the children and if say the total estate was £570,000 at the time then 40% inheritance tax would have been payable on £285,000 of it ie half of the estate as inheritance tax kicked in when an estate got to £285000.
If the one spouse left their £285,000 to the children and the other spouse left the other £285,000 when they passed away later then no inheritance tax would be payable.
It does make the house unavailable for care home fees as the house can not be sold without the consent of the children as they will have right of occupation.
It also prevents a spouse getting a partner and passing on the other spouse's share to them.
There are a lot of gold diggers even amongst elderly people looking for money for their children.