Kashrut

Meat and Dairy

It is a long-established Jewish tradition, documented unequivocally in the Talmud (well before the emergence of any separate S&P customs!), that the three biblical references to not searing a kid in its mother's milk are interpreted as three distinct prohibitions:

Poultry: At a rabbinic level, it is customary to consider poultry as meat. 

The other way around: Eating meat immediately after dairy is allowed with just a minimal wait or drinking something to clear the palate.

Differences between communities, however, emerge when it comes to the question of how long one is rabbinically required to wait after eating meat, before eating dairy.

How long to wait: There are a wide variety of customs amongst Jewish communities in this area, including some that distinguish between the wait after red meat and the wait after poultry. 

The Jewish legal commentaries speak of "the custom of the Jews of Amsterdam", to wait only one hour between meat and dairy food, but it seems likely that this was not the general custom in the S&P community, though it was - apparently - among a section of it.  There are S&P (and Ashkenazi) Jews from Amsterdam today whose tradition is to just wait one hour. This offers the rather attractive possibility of a Friday evening meat meal, followed by a study session or discussion,  and then - after an hour - a decadent, dairy desert!

I am not aware of the one-hour custom having been observed in London, however. There it is more common to wait three hours, but certainly not the six hours often considered today to be the more "correct" ruling. 

Meat and Fish

There is no biblical prohibition against eating meat and fish together. However, in Talmudic times it was commonly thought to be a health risk, and as a result a widespread Jewish custom developed of not eating the two together in the same course. This is not a biblical or even rabbinic prohibition; it is simply a piece of talmudic-era medical advice. Whether or not such advice is in any way "binding" on later generations who may consider it outdated and proven incorrect, is a matter of dispute. In any event, the common practice of eating a meat course immediately after a fish course (with clean cutlery and crockery), merely separating them with a bite of bread and some drink, indicates that the supposed health risk was fairly minor. 

The recipes below are from a manuscript of a kosher family recipe book of the Lopes Suasso family of The Hague, by Jacob Lopes Suasso, who lived from 1767-1830, and was descended from a distinguished Portuguese Jewish banking family. They are clear evidence that the custom of not eating meat and fish in the same course was not observed.

"Briga style" beef

The beef is cooked in red wine and served with a sauce of anchovies, capers and mushrooms.

Beef Hachee (stew)

Dice the beef and cook it in broth with thyme, marjoram and anchovies. To eat with toast.

 Salmon Pie with Meat and Molijges (mushrooms)

Measure a good filling of minced veal, lay it on the bottom of the pie in a layer. Take salmon, season it well and lay it on the meat with slices of lemon, truffles and morilles. On top of this another layer of meat, then another of salmon. Bake it in the oven until it's done.

In England, steak is frequently served with Worcestershire (pronounced "wooster") Sauce. The most famous brand is Lea and Perrins. The sauce is approved as kosher by the London Beth Din, but their approval is accompanied by a proviso that since it contains anchovies, it should not be eaten with meat. 

This has led to the production of a kosher Worcestershire sauce by a South African company, that is fish free for using on steak.

Some American kashrut organisations do allow Lea and Perrins with steak, because the fish content is so small.

Obviously from an S&P point of view, there is no problem in the first place.

Fish and Dairy

There is no biblical prohibition, or even established rabbinic prohibition, against eating fish and dairy foods together. However a custom did develop in some Sephardi communities to refrain from this. 

As pointed out by Kaf Hahayim and others - this custom is based on a printing error. A reference to not eating fish and meat together was accidentally changed to fish and milk. Despite the reference clearly being an error, some middle-eastern communities adopted the custom of not eating fish with dairy (some make an exception for butter and cheese), based on the opinions of some late 19th century medical men who felt that this combination poses a health hazard.

This stricture was never adopted by the S&P, and indeed it seems hard to justify anyone observing it today, when we are sure there is no health risk involved.