The traditional unit for the measurement of areas of allotments is the pole, or sometimes the rod or the perch. They are identical but the one used in allotment legislation is the pole. While the use of these archaic units can be confusing, what is even more confusing is that while these are units of area, there are units of length with the same names. So strictly speaking a pole when used to describe an area is a square pole, but it is rarely described as such; to decide whether lengths or areas are being described you need to know the context.
A length of one pole is 5.5 yards. The length of a cricket pitch is a chain, which is 4 poles, while a furlong is 40 poles.
An area of one pole is that of a square whose sides have a length of one pole, that is 5.5 yd by 5.5 yd or 30.25 sq yd.
An area one chain in width and one furlong in length is an acre, which was approximately the amount of land that in the Middle Ages could be ploughed by a man and an ox in a day. The rod was the ox-goad the ploughman used to control his team, and to reach his leading pair it had to be sixteen and a half feet long, five and a half yards.
The traditional standard allotment plot has an area of 10 poles and allotment legislation considers that 40 poles is sufficient to feed a family.
If you prefer to live in the metric world, then 1 pole is a wee bit over 25m², so a standard plot has an area of about 250m². It is believed that the law now requires us to live in this world. In particular, although we can describe the area of our plots as being so many poles, we should quote rents and charges in pounds per square metre. So those shown on our rents and charges page, are now given in both.
For further reading about archaic measurements, there is plenty on the Internet, for example here.