Due to the <https://en.wikipedia.org/wiki/International_yard_and_pound International yard and pound agreement of 1959>, it so happens that Imperial and US customary units of weight have the same base (the international pound at 0.45359237 kilograms). However, if subdivisions are generally the same, Imperial units feature different multiples of the pound, due to the presence of the stone. As in, using English conventions, the hundredweight is the *long* one (the short one is the cental). As is the ton. Also, of the troy system (the international one being, more or less, the avoirdupoids one) only the ounce is legal.

Where possible, reference have been made to UK legislation. However, Wikipedia's page is much better organized than any government resource immediately available.

The UK legislation used as references are as follows: http://www.legislation.gov.uk/ukpga/1985/72/enacted http://www.legislation.gov.uk/uksi/1994/2867/schedule/part/VI/made http://www.legislation.gov.uk/uksi/1995/1804/schedule/made