The meal called tea served with cold meats, vegetables, and pastry, in substitution of dinner.
“A well-understood `high tea' should have cold roast beef at the top of the table, a cold Yorkshire pie at the bottom, a mighty ham in the middle. The side dishes will comprise soused mackerel, pickled salmon (in due season), sausages and potatoes, etc., etc. Rivers of tea, coffee, and ale, with dry and buttered toast, sally-lunns, scones, mufflins, and crumpets, jams and marmalade.” —The Daily Telegraph, May 9th, 1893.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894