You may struggle with that one:
http://www.coins-of-the-uk.co.uk/monarchs/geor6.html
The Penny
The first design was issued from 1937 to 1940, and then from 1944 to 1948. All these dates are common. During 1940 the exergual line was doubled. Pennies struck between 1941 and 1943 were all dated 1940.
Between 1944 and 1946 the tin content of the bronze was reduced from 3% to 0.5%. Because this alloy tarnished unattractively these coins were artificially toned before issue.
http://wiki.answers.com/Q/What_is_th..._British_Penny
They did Ha'pennies & Irish pennies in 1942 but can't find any images of a 1942 penny