Puttees
For most armies of the world at the begining of the 20th century knee-length leather boots were what was in fashion for their troops. The British army however had to work to a budget since Britain's main military power was traditionally her navy. Instead of tall leather boots, the British soldier wore ankle boots and puttees. These were 9 feet long lengths of wool serge that were wrapped around the legs (from ankle to knee for infantry and the opposite way for cavalry). They had a length of cotton at their top end which was wrapped around the leg and tied off to secure them. At the outbreak of war the troops wore curved puttees that were bent in opposite directions so as to conform more easily to the soldier's left and right leg. Many manufacturers replaced these with straight cut puttees which were much quicker to produce, although they had to be worn in by the troops. Officers would often privately purchase better quality ones. The most common brand was 'Foxes.' These were better made than that issued by the Army and can be easily identified by a small brass disc at the bottom edge which marks each puttee as 'L' and 'R' respectively. The colour of puttees seems to have varied through a range of drab browns and greens. Interestingly, ankle boots and puttees were much better suited to the muddy conditions of trench warfare and by 1918 most armies had adopted them. While originals can still be found it is recommended that they not be used at events where they are likely to have a hard time. Instead buy a reproduction pair or make them yourself by buying three of the (post war) short length puttees, which are widely available, and sewing them together.
Boots
The standard issue boot was the B5 'ammunition' boot. It was made of thick roughside out leather with wooden pegged soles and was ankle length. On home service they were issued in black, but on active service they were issued in cheaper brown (apart from for the Royal Artillery who were apparently issued black ones throughout the war). The soldiers would have to black them up for parades. The laces were also leather. The boots were studded by the Regimental cobbler and so a variety of patterns and styles are seen. Either a pair of leather soled Navy deck boots (made up untill the 1990's) or a new reproduction pair (better but much more expensive) make a good subsitute to the originals.