Royals have coffins made while still alive with Queen's lead-lined one made 30 years ago

ok.co.uk:

Mourners are seeing it for the first time this week, but The Queen's lead-lined coffin was actually made more than 30 years ago.The coffin, which arrives in London on Tuesday as it continues its journey from Balmoral, is constructed from English oak and lined with lead.This is a traditional design choice of the Royal Family as the use of lead helps to preserve the body longer by making the coffin airtight and stopping moisture from building up.

With the coffin placed in a vault rather than buried underground, the lead has an important role. According to The Telegraph the Queen's coffin was made three decades ago, along with a matching one for her late husband Prince Philip, the Duke of Edinburgh.

The concept of lead lining can be traced back to the Victorian era, when protecting bodies in an airtight coffin was necessary to protect bodies when they are laid to rest above ground.

It means the Queen's coffin, which is draped in the Royal Standard, is very heavy and will require eight pallbearers, rather than the usual six.