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far as could be seen, a clean bill of health, and giving no special features
needing comment. The exception was a girl who, for the particular week
which included the dates on which the two batches of meat pies thus far
incriminated were baked, had taken the place of the employee usually responsible
for the filling of the meat pies with gelatine. This coincidence as
to dates in connection with an operation which, as shown below, was a
critical one in the manufacture of the pies, at once threw suspicion on the
temporarily transferred employee as a likely source of infection. The closest
enquiry into her antecedents and history gave, however, no reason to suspect
her health, and examination of her blood, and subsequently of stools and
urine, gave entirely negative results as regards any paratyphoid infection.
It should be added that the blood of every member of the staff, so far as
then known to us, was examined for paratyphoid infection, as were also the
stools and urine of certain members most closely connected with the process
of pie-making, but in all cases with negative results. The search for a
human source of infection had therefore, for a while, to be left at this
negative stage.
Process of manufacture of meat pies.—Veal and ham pies were the only
type of meat pie made. Two batches were baked each week, on Tuesdays
and Thursdays respectively. These were issued immediately after each baking
to the various branch shops, except that a small number were stored overnight
at the bakery owing to difficulties of transport to three branches. The
greatest individual number of pies were sent each week to the branch with
which all the initial cases had been connected. During the week which
included the bakings of August 25th and 27th, this branch received nearly
four times as many as the average number of pies issued to any other
branch.
It is necessary, for reasons which will become apparent, to give a brief
description of the process of manufacture of the veal and ham pies.
The veal and the ham, obtained respectively from two Croydon butchers,
were chopped, minced by machine and mixed by hand ; to these were added a
paste, made of stale bread, rubbed into crumbs by hand, and mixed by hand
with water and herbs, the whole being mixed by hand into a large heap
and weighed out into suitable portions. Dough, made by mixing flour,
water, lard, and yeast in a mechanical mixer, was rolled out by hand, cut,
and filled into tins as a lining for the bottom and sides. The portions of
meat paste were placed in the dough-lined tins. A cap of dough was
applied, painted over with egg solution made from frozen whole eggs, and
two vents made in this cap. The tins were then placed on metal trays and
heated in a brick oven at about 400° F. for two hours. Meanwhile, a bone
stock made from bones (supplied by a Croydon butcher), with water and salt,
was prepared by boiling the mixture in a metal utensil for 45 minutes, and
then allowing to simmer for two hours. The bone stock was run into a large
basin, powdered gelatine—swollen with water—added and allowed to melt
without further heating, a seasoning of salt and pepper stirred in, and the hot
mixture run into a large jug and poured by means of a funnel through the
vent-hole into the baked pies till these were filled with jelly. The pies were
then placed on metal trays, taken into an adjoining room, there placed by
hand on wooden trays covered with paper, and the wooden trays, with their
contents loaded on to motor vans, which conveyed them to the various
branch shops, the trays being then removed from the van and taken into the
shop, the pies being stored on the trays without further handling until sold
to the customer.
The veal, ham and bones were traced back to the butcher's shop supplying
them, but nothing of note was discovered; it was obviously impossible
to ascertain whether the particular supplies used for the batches of pies
baked on August 25th and 27th were sound. Similarly, nothing of