Somehow, in English language armoured history, the index "Matilda I" managed to latch onto the Infantry Tank MkI despite some evidence to the contrary. Interestingly enough, this never happened in Russian literature. Here is a page from the Tankomaster magazine, February 1991 edition, listing the A indices of various British tanks.
Holding up this list against the Wikipedia one, it seems identical... almost. In this list, the A11 is not a Matilda, only "Infantry Tank MkI". Soviet wartime documents would have still been classified, meaning that the "nameless" MkI had to have come from an English source. Several other traits hint to this, including referring to the engine on the A16 as "Nuffield Liberty" (contemporary Soviet sources just called it "Liberty") and the transliterations rather than translations of "Centaur", "Cromwell", and "Tortoise".