Jam and cream, in its tea-table form, is the cream tea folded down into an afternoon-tea finger: thin soft bread, a measured layer of clotted or whipped cream, a thin stripe of jam, trimmed crustless and cut into small fingers meant to be eaten in two bites without disturbing a conversation. The defining fact of this reading is restraint rather than abundance. The same components that make an indulgent doorstep elsewhere are here deliberately thinned and trimmed, because the point of a tea-tray sandwich is delicacy, not to fill anyone up. The cream is enough to taste and no more; the jam is a stripe, not a bed; the crusts come off because a crust resists a soft delicate filling and the whole logic of this version is that nothing should resist.
The craft is moisture control and proportion at small scale, where there is no thick layer of fat to forgive a mistake. Cream goes against the bread and jam over the cream, because even a thin cream layer waterproofs the crumb against the jam better than the reverse, and a finger sandwich that wets through in the half hour between assembly and the tray has failed at the one thing it exists to do. The cream is held just firm enough to stay put when the sandwich is cut into fingers; the jam is spread to a film so it does not show at the edges or squeeze out under the knife. The bread is thin, soft, and plain so two bites carry mostly filling and the trim is clean, and it is pressed lightly before cutting so the layers settle into one rather than sliding apart on the plate.
The variations stay inside the restrained tea frame. Whipped cream rather than clotted lightens it further for the tray; a single fruit jam swapped for another changes the note without changing the scale; built thick on a doorstep loaf it becomes the indulgent version rather than the finger. Each deserves its own article rather than being crowded in here.