Danny, your recollection of a Tee Emm poem referring to a SBA visual 'kicker' indicator emphasises yet again one of the major bonuses of this thread, the throw away/BTW comment. Presumably it 'kicked' in time with the modulated dots or dashes and in the appropriate left or right direction.
So, not a variable deflection indicating say a quarter or half beam displacement, but a back up means of assisting the mental processes to get back on the centre line, especially on a back beam!
It seems this was still the technological hurdle to jump, and it took the ILS system to do it. Intriguingly Wikki says that the German SBA/Lorenz system did later feature a directional arrow to indicate direction to turn, but again I suspect that was a 'kicker' rather than displacement indicator. Also interesting that Lorenz was developed into the Elektra-Sonnen Long Range nav system used by the U-boats, and that we knew as Consul post war:-
http://en.wikipedia.org/wiki/Lorenz_beam
It was presumably the ILS displacement technology that was applied to the 'localiser needle like' Violet Picture 243 MHz Sarbe homing system mentioned by Hummingfrog. We had that mounted on the instrument coaming in the Hastings. When Vietnam was raging, a flight from Changi to Kai Tak would see it seemingly welded to the LH stop while flying past Vietnam over the South China Sea, with the RH stop similarly utilised on the return. Listening in, there was even more of a cacophony than with SBA, for Guard was simply a natter frequency apparently. Bad luck for anyone trying to declare an emergency or worse still on the ground appealing for help, having banged out and now surrounded by the Viet Cong...
PS It seems that the ILS system existed pre war,
http://en.wikipedia.org/wiki/Instrument_landing_system
and the Luftwaffe appears to have used it during the war, see this German language page from Wikkimedia ref an AFN2 indicator of 1943:-
http://commons.wikimedia.org/wiki/Fi...t_Peil_G_6.jpg