I don't know enough on this particular subject for a definitive reply. Here is what I do know, in no particular relationship.
- British tankers would use a semaphore system for communication.
- Company/squadron coordination was very good.
- The No. 19 radio was installed in all tanks in 1942.
- The Sherman was a jump in communications capability for the British.
- Robert Crisp (M3/Honey commander) mentioned the intercom system several times in his book, but I don't recall him saying much about a radio.
My conclusion would be that they have a good radio, and a better one later, but it isn't in every tank. Maybe only the platoon/troop commander's tank?
My intended query has more to do with the PG system, rather than history, but both matter.