The Queen's undertakers always keep a special coffin ready in case a member of the royal family dies suddenly abroad.
Leverton and Sons, a 200-year-old firm which was made royal undertakers in 1991, describe the casket as its "first call'' coffin in case of emergencies.
"We have some plans for some members of the royal family and there is an overall operational plan involving repatriation if there is a death abroad or, say, in Scotland,'' said its boss Clive Leverton.
"We have what we call a 'first call coffin' which is used,'' he said. The coffin's design meant it was airtight, said Mr Leverton.
The Queen and her husband the Duke of Edinburgh, who this week celebrated their 60th wedding anniversary, are in the Ugandan capital Kampala for a Commonwealth summit.
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