The Supertunica, made in 1911 for George V and used subsequently by both George VI and Elizabeth II features on the Royal Collection website:



"Provenance:
Supplied for the coronation of King George V in 1911 by Wilkinson & Son of Hanover Square, London.

Description:
A full-length, sleeved coat of gold silk, opening at the front, with a narrow strip and wider band of foliate-embroidered ornament to either side and lined with red tabby silk; with a belt similarly embroidered and with a gold buckle cast with roses, thistles and shamrocks.

This Supertunica was worn at the coronations of King George V, King George VI and Queen Elizabeth II. The Supertunica is the garment worn under the Imperial Mantle. The Supertunica, like the other coronation robes, relates to priestly vestments, and although this particular garment dates from the twentieth century its form has changed little since medieval coronations. This link with priestly robes was a reminder of the divine nature of kingship. The sovereign is invested with the Supertunica following the anointing ceremony."

http://www.royalcollection.org.uk/collection/31793/the-supertunica