Cooling Cups and Dainty Drinks by William Terrington (1869, p.167) — Terrington 1869

1 wholelemon juice — Strained.acid
1 bottleclaret base
3 bottlesSeltzer water — German seltzer waterdilution
1 gillcherry brandy — cherry-brandymodifier
0.5 bottlesherry modifier
cucumber and lemon verbena — cucumber and verbenaother
1 gillport wine — portother
oleo-saccharum sweetener
sugar — Sweeten to taste.sweetener
  1. Combine the claret, sherry, port, cherry-brandy, oleo-saccharum, and strained lemon juice.
  2. Sweeten to taste and flavour with cucumber and verbena.
  3. Strain, ice up, and when ready for use add the iced German seltzer water.

Ice: Ice

The Cambridge and Oxford claret cups are paired in Terrington as competing institutional signatures.

The build depends on a flavoured, strained wine base completed with aerated water at service.

Bartenders' Guide: How to Mix Drinks by Wehman Bros. (1912, p.23)

1 bottleclaret — Claretbase
0.5 bottlesherry — Sherrymodifier
  1. Combine the claret and sherry and serve as a cup.

See also: Oxford Claret Cup, Claret Cup a la Stockdale, Balaklava Nectar Claret Cup

The source gives only the ingredients, so the capture stays intentionally minimal.