Dickens mentions Smoking Bishop in 'A Christmas Carol' and Eliza Acton gives a recipe in 'Modern Cookery' but my guess is that it was popular long before then. Acton's version is elaborate:
Make several incisions in the rind of a lemon, stick cloves in these, and roast the lemon by a slow fire. Put small but equal quantities of cinnamon, cloves, mace, and allspice, with a trace of ginger, into a saucepan with half a pint of water: let it boil until it is reduced one-half. Boil one bottle of port wine, burn a portion of the spirit out of it by applying a lighted paper to the saucepan; put the roasted lemon and spice into the wine; stir it up well, and let it stand near the fire ten minutes. Rub a few knobs of sugar on the rind of a lemon, put the sugar into a bowl or jug, with the juice of half a lemon (not roasted), pour the wine into it, grate in some nutmeg, sweeten it to the taste, and serve it up with the lemon and spice floating in it.
Bishop is frequently made with a Seville orange stuck with cloves and slowly roasted, and its flavour to many tastes is infinitely finer than that of the lemon.
It would need to be a special occasion to want to make that. Modern recipes are a little simpler, but the cinnamon puts me off a bit. There's a lot of cinnamon around at this time of year, and much as I love it, it doesn't have to be ubiquitous. Oxford Bishop recipes definitely favour lemon, which apparently lose their bitterness when roasted, whilst oranges become bitter.
Heath quotes Professor Saintsbury
''It is, as I have found more people not know than know in this ghastly thin faced time of ours, simply mulled Port. You take a bottle of that noble liquor and put it in a saucepan, adding as much or as little water as you can reconcile with your conscience, an Orange cut in half (I believe some people squeeze it lightly) and plenty of Cloves (you may stick them in the Orange if you have a mind). Sugar or no Sugar at discretion, and with regards to the character of the wine. Put it on the fire, and as soon as it is warm, and begins to steam, light it. The flames will be of an imposingly infernal colour, quite different from the light blue flicker of spirits or of Claret mulled. Before it has burned too long pour it into a bowl, and drink it as hot as you like. It is an excellent liquor, and I have found it quite popular with ladies.'I like the relative simplicity of this version (no oranges need roasting for a start), burning it will reduce the alcohol which is probably a good thing, as well as being theatrical. I haven't tried this yet, but it sounds like just the thing for Boxing Day, or New Year's Day - sometime when there are enough family or friends around to drink it with, but at the point where it's acceptable to read a book or watch a film.
It could be almost any Victorian book I can think of to fit the mood of this drink, but Bishops mean Barchester, and Trollope to me, and the pared down Saintsbury/Heath recipe also seems more Trollope than Dickens. It would be another sensible use for a bottle of ruby port, and would certainly scale down to half bottle quantities without any difficulty.