I think the Nighlingale NM1 speakers were originally designed specifically for Jeffries Hi-Fi in Sussex.
They were one of the first multi-driver speakers to pay attention to the phase arrangement of the drive units. The NM1 used a KEF 139 bass unit in a transmission line enclosure, with open baffle Peerless K040 MRF mid range and Isophon KK8/8 tweeter.
