Lieutenant Charles Lister, Hood Battalion, 2nd Naval Brigade, RND - Lister was an amusing correspondent and on 18th July he wrote a typical letter which manages to be amusing about both Scotsmen and jam manufacturers.
"We are now in the trenches. We went in about three days ago. They are old Turkish trenches, with one or two admirably protected dug-outs, which we suspect the Turks have been made to hollow out for the German officers. It is fairly whiffy, and there are quite a number of dead in the neighbourhood, and the tell-tale stocking or end of boot is now and then seen protruding from the trench wall. We get our share of sniping, even in the support trench, which I have seen most of. One has to drop nimbly past certain critical corners. But there is no need for anyone to get hit if they keep down. The Turks are sniping from a long way off and fire on the chance. The communication trenches are rather ticklish by day, though safe enough by night. There are occasional dead bodies where people have been killed, and it is an awful job getting our men past them: they have a sort of supernatural fear of trampling on their own dead; this kind of feeling of awe is felt also by the men in the case of the Turkish dead. We get all we want to eat. The Eastern tea and biscuits and jam are excellent, but for a jam variety known as the Sir X. Y. brand, with a picture of the inventor on the label. He is a characteristic Millbank type, with the urbane glance of the sweating mill-owner of the 'forties. I-le gives us away, because the French used to give us wine in exchange for jam, but are now tired of doing so, as they always get this sample foisted upon them. What a good example of Gresham's Law. Trench life means a good deal of repose but very little sleep. This is not so much due to the enemy as to the torrents of raw levies coming up to do working parties or to relieve pals or to look for their proper places in the line, and so on. I have had my toes trodden on by every officer and man of a Scottish Territorial Division. They come up in driblets, carrying the most weird cooking utensils, and with every sort of impedimentum. They never know how many of them are coming, and if you ask them each man says he is the last. Then after about ten seconds' interval fresh men come up, carrying what appear to be portions of bagpipes. They are always getting lost and held up. Last night I had to get them out by dint of jumping on the top of the communication trench parapet and kicking dust on to their heads, and at the time using the most violent language. The humours of trench warfare are really delicious. Our men are in fine fettle and have worked awfully well, taking things up to the firing-line with hardly any rest. Patrick keeps a most lucid grasp of affairs, even with the Scots standing on our toes, when the trench is a seething mass of humanity. I had no idea the difficulty of getting men in or out of the trenches would be so great. The trenches are bone dry just now, rather hot and dusty, but there is always a breeze. I am very well and happy. The trench soil is limestone and chalk, rather white and trying to the eyes."
With regard to the jam tins I think Lister may have been referring to Henry Jones a jam manufacturer from Australia who had adopted the brand name IXL (I excel in all the products that I make - Lister would disagree!) and was himself popularly dubbed 'Jam Tin Jones'. As a brand name this motto was an inspired choice soon forming part of Tasmanian and Australian folklore. It became instantly recognisable with the man, his factories and his products. He was the largest private employer in Tasmania and at the time, the head of the largest private company in the world exporting jam to countries throughout the world. With this and his contribution to commerce and military efforts, he was the first Tasmanian to be knighted and hence became caricatured as the 'Knight of the Jam Tin'. As to Gresham's Law it seems that Charles Lister was far better educated than I am (Eton seems to be superior to Chesterfield in this respect!) However I have looked up Gresham's Law and found that it is an economic principle "which states that when government compulsorily overvalues one money and undervalues another, the undervalued money will leave the country or disappear from circulation into hoards, while the overvalued money will flood into circulation." It is commonly stated as: "Bad money drives out good". This law applies specifically when there are two forms of commodity in circulation which are required by to be accepted as having similar face-values for economic transactions. The artificially overvalued money tends to drive an artificially undervalued money out of circulation. Gresham's law is named after Sir Thomas Gresham (1519-1579), an English financier during the Tudor period.
C. Lister quoted by Lord Ribblesdale, Charles Lister: Letters and Recollections (London: T. Fisher Unwin Ltd, 1917), p.209-210