The name of the preacher "Jimmy Mundy" alludes to the famous evangelist of the day, Billy Sunday (1862 - 1935).
When Chiswick complains about the quarter that Bertie gives Mr Coneybear, he says that it was equal to a shilling, and based upon other comparisons of Sterling with US currency, this is close. Previously, Tuppy had written a cheque for Mr Stoker to pay for the 48 cars he ordered, to the value of $57,000, which he tells Bertie is exactly £10,203, 14s 4d. This works out to be 2,448,892 pence, and dividing this by 57,000 would give the value of one United States dollar, which is just under 43 pence, meaning that one fourth of this, the value of the quarter Bertie gave to the lift man, would equal just over 10.74 British pennies, so just a bit less than the whole shilling. This comparison gets closer over the years, such that in about 1944, one pound equalled just under four dollars, and now, the pound is equal to $1.22.