Also, until March, 1964, WNAC-7 Boston transmitted from a tower much shorter than that of the other Boston VHF stations.
If the North Adams cable headend was atop a mountain, it may have been possible, with a very powerful antenna and signal amplifier, to pick up the VHF channels from Boston off-air. Until March, 1964, such a headend likely couldn't have received a signal from WNAC.