Hi David,
Yup! "Elevated Aerial 30 - 60 Mc/s"
Full kit is "Elevated Aerial 36-60MCS Kit No1 Z1-ZA53380".
It fits on top of the 27-ft telescopic mast and consists of an elevated aerial base with co-ax connector and downlead, a length-adjustable vertical element (frequency marked), and three replacement top guy assemblies that include a wire section that acts as a ground-plane for the vertical radiator.
If you need to shift frequency dramatically you also have to lower the mast and adjust the vertical element to the new frequency, then raise the mast again.
The 27-ft telescopic mast is an unfriendly beast: very heavy, the rigging kit weighs more than the mast, and it has a nasty habit of lowering itself very rapidly if you don't tighten the collars, or let the mast slip when adjusting it.
Mind Your Fingers!
Mast kit comes with an extremely heavy base spike, a flat plate for vehicle roofs, and there were special "bumperette" mounting kits for Land Rovers - a mast socket and a clamp that fitted the hoops.
(The Clansman-era equivalent used a "pineapple" adapter that had a resistor network inside; this had the effect of reducing the reflected power where the aerial length did not suit the frequency in use, protecting the set - it also got hot in those circumstances and was visible in infra-red! (High power sets could also burn it out, so it's advisable to test before buying a used one.)
The gain in effective range was worth the reduction in transmitted power, and the removal of the need to adjust the aerial length in use was a great improvement.)
Chris.
(There was a lower frequency version available for other sets, covering 23-38Mc/s.)