Ok, this is my final thought on speaker shopping! Maybe... Just had confirmation that my Trinity Deluxe kit is en-route, so exciting stuff...now I just have to build it. Help WILL be called upon!
Anyway, in some internet searches, discovered Tayden speakers, True Brit 12" - which is described as offering '1960s creamy blues tones'. Sounds similar to the Celestion Greenback description, which bgroup described as 'awesome'. And its British, hand made, so will boost our ailing economy!

Looks nice too, in British Racing Green!
And then I can always upgrade to the gold standard Tone Tubby Alnico! Just thought I'd post in case anybody had heard of them, used them and wanted to tell me I was about to make a huge schoolboy error in using them in a Deluxe!
R