I think Fergus Fitgerald the head brewer at Adnams tried culturing up that strain in the past and didn't think it was too close. But he said that it could be an isolate from their yeast in the 80s when it was more like 5 or 6 strains. That's what I recall from maybe a twitter convo he had. I'll try and find it
edit: found this it was about the wyeast version
https://twitter.com/Solebear/status/560553728512892928
https://twitter.com/Solebear/status/1006218973111865344
they continuously reculture one strain and add it to cropped yeast and also restart both strains from scratch
I know on Jims that a few people have used their primary yeast from minikegs and that if they repitch it it goes very attenuative very fast
and confirming that it used to have more strains
https://boakandbailey.com/2013/10/ancient-adnams-tally-ho/#comment-36602
edit: found this it was about the wyeast version
https://twitter.com/Solebear/status/560553728512892928
https://twitter.com/Solebear/status/1006218973111865344
they continuously reculture one strain and add it to cropped yeast and also restart both strains from scratch
I know on Jims that a few people have used their primary yeast from minikegs and that if they repitch it it goes very attenuative very fast
and confirming that it used to have more strains
https://boakandbailey.com/2013/10/ancient-adnams-tally-ho/#comment-36602