@Zulu Alpha: I'm assiduously watching eBay at the moment
@A and C: Thanks for your input. There's a (rather costly) set of ANR converted DCs on eBay at the moment but for possibly rather more than I'd like to pay. Bearing in mind I've done without ANR for a quarter of a century, and only do fifteen to twenty hours a year, it's probably not worthwhile getting them.
Thanks to all for the advice though!