Definition of postal draft in US English:

postal draft

noun

British
historical
  • 1In 1914 the form used at Post Offices for the payment of Navy and Army Separation Allowances, later called ‘allowance form’.

  • 2A draft or cheque drawn on the Postmaster General, introduced in January 1925 for the payment of National Health Insurance benefits, and later extended to certain government departments.

Origin

1920s; earliest use found in Post Office Guide.