In accordance with the Postal Order Regulations of 1961, postal orders may be issued for the following sums:
The sum of 50 pence; and
The sum of one pound and any multiple of one pound up to ten pounds
The value of a postal order may be increased by affixing postage stamps not exceeding two in number and not exceeding a total of 49 pence or the equivalent in coinage of the country in which the order is issued. Any such stamp may either be a stamp authorized or required to be used for the purpose of the post office or, if the postal administration of the country in which the order is issued so allows, a current stamp for denoting a rate of postage of that country, but no other stamps may be used.
A charge for poundage is applied according to the rates applicable when the order is issued.