British Foliage/dapple (Mickey Mouse) pattern would be good. Similar to the firefly mentioned earlier.
It was used more to avoid aerial observation as it changed the profile of a vehicles shadow. If you want to be really historically picky then you could say that this pattern was mainly used on trucks/transports not tanks but the specification did not rule out its use on armored vehicles.
images:
http://www.miniature...se-pattern.html
http://www.flickr.co...in/photostream/
Historical reference:
quote taken from
http://www.mafva.net...tarmer camo.htm
1942- 44 – M.T.P. 46/4A introduce new toned schemes aimed primarily against aerial observation, usually using the BS.987C browns as laid down in A.C.I. 1160 of May 1942. The most common versions were variants of the ‘Foliage’ pattern and the ‘Mickey Mouse’ variant of the ‘Dapple’ pattern. Vehicles continued to be delivered and used in plain S.C.C. 2 following A.C.I. 1160 which gave S.C.C. 2 as “Basic Paint”. In October 1943 A.C.I. 1496 authorised S.C.C. 14 (black) as the main shade over S.C.C. 2.