It’s not really though, is it? Any more than who pays for polling or advertising or any manner of other things in politics is incidental. And, as above, they would hardly have released the opinion if it hadn’t suited their aims.
No, you don’t need to “shop around”. You go to the QCs that you already know will back your side of the argument (I gather that some QCs are even quite vocal on twitter about their opinons these days). I know, from experience, that’s exactly how it works.
Anyway, this is an impossibly dull sub-thread on an extraordinarily dull subject, so probably best to agree to disagree on this one. No hard feelings.