In addition to those struck at the Royal Mint, in 1912, 1918 and 1919 some pennies were produced at the Heaton Mint in Birmingham, and are identified by an "H" mint mark to the left of the date. In 1918 and 1919 some were produced at the Kings Norton Metal Co. Ltd, also in Birmingham, and have a "KN" there instead. Both firms also provided blanks to the Royal Mint for striking into pennies from 1912 to 1919. This was due to high demand for small change, initially caused by the 1911 implementation of the National Insurance Act by the Asquith government, and thereafter by the war years. Also feeding the demand for pennies were automatic slot machines, a trend noticed as early as 1898. To reduce the number of worn pieces in commerce, the Royal Mint had in 1908 agreed to accept the return of worn pre-1895 pennies and halfpennies through banks and post offices, and from 1922, pieces dated 1860 to 1894 would be redeemed in any condition, though they remained acceptable in circulation. The pre-1860 copper penny had been demonetised after 1869 in Britain (though accepted at full face value by the Mint until 1873) and in 1877 for the colonies.