I've never seen details of the Teletron coil on the internet, but I don't think my example uses Litz wire. For myself, I think the choice for a substitute - to remain in the spirit of the original design - lies between a) the Repanco DRR2 and b) a homebrew toilet-roll technology coil such as I describe on my site (see first post on this thread).
a) The Repanco coil (whch might be as scarce as the Teletron, but was in manufacture later) has no aerial winding as the Teletron does, but has a tapped medium wave winding, a long-wave winding, and a reaction winding. Davey specified this coil for later versions of the design when the Teletron went out of production.
b) The homebrew coil using ordinary enamelled wire on a 2" former is based on a Davey design, and gave me similar results to the Teletron coil. Its size make it necessary to offset the valve from its dead-centre position as shown in the BBC design.
By the way, I'm keeping my eye on another thread -
https://www.vintage-radio.net/forum/...light=BBC+coil
where the same topic is in danger of being discussed in duplicate. Moderators - help!