Taken from the above book
Afternoon tea is one of a pair of meals (the other being high tea), both of which are essentially British and which, although alike in having tea as the beverage served, stand in high contrast to each other in other respects.
Mrs Beeton expressed succinctly the material difference when she remarked that "There is Tea and Tea" and went on to say that ' A "High Tea" is where meat takes a more prominent part and signifies really, what is a tea-dinner.....The afternoon tea signifies little more than tea and bread and butter, and a few elegant trifles in the way of cake and fruit'
Although the custom of taking a cup of tea, at least occasionally, at a suitable time in the afternoon may have been adopted by some ladies in the late 17th century , it seems clear that neither afternoon tea nor high tea, the meals, started to become established until late in the 18th or early in the 19th centuries. Since almost all authors rely on the indefatigable Ukers, who had scoured available literary and artistic sources for indications on this point, he must be allowed here to speak for himself:
Dr. Alexander Carlyle wrote in his autobiography of the fashionable mode of living at Harrogate in 1763 that, "The ladies gave afternoon tea and coffee in their turn. 'For the custom of afternoon tea as a distinct and definite function, however, the world is indebted to Anna, wife of the seventh Duke of Bedford, 1788-1801. In her day people ate prodigious breakfasts. Luncheon was a sort of picnic, with no servants in attendance. There was no other meal until eight o'clock dinner, after which tea was served in the drawing-room. The Duchess of Bedford struck out a new line; she had tea and cakes served at five o'clock, because, to quote herself, she had a sinking feeling'.
Fanny Kemble, the actress, in her Later Life, records that she first became aquainted with afternoon tea in 1842 at Belvoir Castle, seat of the Dukes of Rutland. She added that she did not believe the now universally-honoured custom dated back any further than that.
In the 20th century afternoon tea kept to a formula:
tea (loose leafed and in a pot)with milk and sugar, or perhaps lemon if China tea is served; dainty small sandwiches (cucumber very thinly sliced, is a favoured filling); scones with butter and jam (optional); some form of little cakes or slices of a large cake; biscuits (optional); and a serviette or napkin to complete the picture. The effect is charming and may be achieved by a hostess (or host) with far less expenditure of effort and money than a full meal, or even a high tea, would require.
A variant of afternoon tea is the Devon cream tea, which towards the end of the 20th century was advancing relentlessly across all the other counties of England, and indeed appearing in Scotland, Wales and Ireland, sometimes described as just 'cream tea'. This calls for scones, clotted cream, and jam.
As Harrogate was mentioned in this writing, you might like to visit my post showing the famous tea rooms there