Royal Armoured Corps "red - white - red" stipes (Flash) was used on British tanks upto and through D-Day.  It was a carry on from WWI.  It was eventually replaced by the application of the Allied Star in 1944.  
 
The "Crusader" variant "white - red - white" flash originated in 1941 during "Opperation Crusder" the relief of Tobruk. All participating armored units were ordered to mark their tanks with a large and distinctive easily recognized marking due to a number of factors including the enemy usuing captured British tanks.