If late 80s will do...
Like this
https://www.ebay.co.uk/itm/164992651...6&toolid=10001
only khaki beige in colour, and a slightly different attachment clasp- double barrier to undo, rather than the pin.
Almost always attached to the ring on the MGB, giving enough length to get into the jump seat. An instructor would suit himself as to whether to use the MGB or a floor ring. Can honestly not remember a pax in a dispatcher's harness.
CG