This article is about a boxed set of silver plated flatware, shown in a picture at the end of the article, and the problems for an American trying to read its marks.
The owner thought this type of boxed set was properly called a canteen.
Not so. A canteen is simply a set of tableware often with 12 place settings. A half-canteen has 6 place settings and a double canteen has 24. There are other sizes and often any boxed set of silver tableware may be properly labeled as a canteen.
Canteen in English translates simply to a ‘set’ in American. The set may be in a box.

A dessert boxed canteen with 6 forks and 6 spoons made in Sheffield by James Dixon & Sons in 1905, in the reign of Edward VII. A canteen does not have to be accompanied by or contained in a fitted box. (see note 1)

Much of the information on this page came from a web site that is very informative (see note 2).

The box containing the silver may have its own maker’s mark.

Starting with the box: Makers mark on author’s canteen box. The Army and Navy Co-operative Society Ltd was formed in 1871 by a group of army and navy officers. It was their intention to supply 'articles of domestic consumption and general use to its members at the lowest numerative rates'. The first store opened on 15 February 1872 at Victoria Street, London. At the end of 1873 a gun department was established. The contents of the box were probably made after 1872. And also before 1934.

By the end of the century the Society was issuing an enormous annual illustrated price list, had introduced telephone ordering and had reduced mail order prices. In 1934 the company's official name became the Army and Navy Store Ltd and in 1973 Army and Navy Stores was taken over by House of Fraser. (Taken from Michael Moss and Alison Turton, A Legend of Retailing, House of Fraser: London; Weidenfield and Nicolson, 1989.)

It is possible this box and contents were assembled by the Army & Navy C.S.L. as the pieces inside are of 1900 to 1910 manufacture by William Hutton & Sons in Sheffield, England.
The knives, all but one, were made for the Army and Navy C.S.L.
It was a practice of English officers to travel with a canteen of silver to entertain in a proper fashion and style when posted to distant parts of the English Empire.
The oak box would have made a good companion piece to the wooden campaign chests, desks, and beds with which they also traveled.

Other terms used to describe a canteen are:
straight, meaning all the spoons and forks are of the same dates, and mixed, meaning there will be some variation of the above.
This canteen is straight with the exclusion of one knife.
All the silver has one maker, William Hutton and Sons, all are close to the same date 1900-1910, and are of the same pattern, simple English.
The knives in such an officier’s set can vary even more. The blades may be of steel, stainless steel, or silver (rare). The handles may be of silver, ivory, bone, or a plastic made to look very much like bone. One knife out of 24 in this set is not by the same maker.
In this canteen the blades are steel, the handles are not silver, and considering the date of 1900-1910 would be of ivory or bone. Perhaps a reader can tell us.

The terms Sterling and solid silver mean at least 92.5% of the article was silver. The assay mark was distinct for each English town which had an assay office and each piece of solid silver ware to be sold was assayed and punched if acceptable or destroyed if not acceptable.
During the late 1700s these were primarily London, Birmingham, Sheffield, and and Chester. This set is not sterling.

The Sheffield Plate process involving heat fusion of two metals was discovered by Thomas Boulsover in 1743 and made a commercial success about 1748-1750 by Josiah Hancock. This process allowed the ownership of silver household wares to move from the very rich (Sterling) to the entire upper classes.
Fine Silversmith firms soon made both types of wares. The solid silver had an assay mark indicating the amount of silver in the article.
The Sheffield Plate did not. It also did not have a duty mark as the firm did not pay a tax to the crown for each piece produced. Some cities such as Glasgow, Scotland, and York, England did use town of origin and date marks. Sheffield Plate did not have date marks. This set is not of Sheffield Plate.

The Electroplating technique was discovered piecemeal and in 1840 the firm of Elkington & Co. of Birmingham acquired all the available patents. Shortly thereafter William Hutton obtained from Elkington and Co. the right to use this technique and while already producing Sterling and Sheffield Plate, now added Electroplate wares.
Electroplating soon thereafter became a serious competitor of the fused Sheffield Plate and made the ownership of fine silver household pieces available to the middle classes.
Sheffield Plate and Electroplate were only silver on the outside but made the same fine appearance on the table or sideboard.
Sheffield Plate held a firm place in the market until 1840 (nearly 100 years) before production all but ceased in favor of the less expensive and often more durable Electroplated wares.

The Sheffield electroplating process, as available from firms paying the required royalty to the Elkington firm, held sway from 1838-1840 to a little after 1900. Other electroplating techniques then supplanted the original. How was this set dated to 1900 or shortly thereafter?

Queen Victoria's reign (1837 - 1901) has given the name Victorian Plate to silver plate made in England by the original electroplating method during these years.

In this set the silver markings are identical on all the forks and spoons. These are not sterling, and though made in Sheffield, are not Sheffield Plate. They are electroplated silver from Sheffield, England, made between 1900 - 1910 by the firm of William Hutton and Sons.

These are marks used on William Hutton & Sons British Plate Metal Plate (?) A B or C quality(?) It is assumed that MP stands for metal plate.

As assay, date and duty marks were not used on the Electroplated Sheffield wares, the Makers mark is the main source of hints as to a date more precise than 'Victorian'.
This canteen containing Victorian Plate by William Hutton and Sons is dated rather precisely to 1900 to 1910 by the maker’s mark.
William Hutton made fine solid silver pieces, fine Sheffield plate pieces, and fine electroplated pieces.
The Creswick firm did the same. William Hutton and Sons’ marks varied depending upon whether the article was Sterling, Sheffield Plate or Victorian Plate.
Above are examples of some of his marks used on Victorian Plate (see note 3).

In 1900 William Hutton bought out the Creswick firm and for no more than 10 years he continued the use of their mark preceding his own firm's mark (see note 4).

The mark reads:
8 crossed arrows (4x4) registered to the Creswick firm and transferred to William Hutton when he purchased that firm,
WH & S for William Hutton and Sons,
B P in old English Script [perhaps resembling date and town marks] but meaning British Plate.
MP over A1. The MP is not identified yet. A good guess is Metal Plate. The A1 is a quality mark with the same meaning it has today. In the maker’s opinion this was the highest quality his firm made.

After approximately 100 years there is no apparent wear to the silver plate and no area has exposed nickel alloy base metal.
 

Endnotes
(1) http://www.payneandson.co.uk/as_stock/50-1535.html
(2) http://www.antiquesilverspoons.co.uk/canteens.htm
(3) The book of Sheffield plate - Wyler 1949 - Crown Publishers USA
(4) information supplied by Gary Bottomly