"Sisson was able to be cross examined by Collinson on all issues...

"Sisson was able to be cross examined by Collinson on all issues - it was up to Collinson to robustly cross examine him if he thought appropriate, not Borksi."

More to the point, Collinson did cross examine Sisson, and, at one stage, committed the fatal error of any barrister - asking a question where he did not know the answer in advance. I don't recall the precise question or the precise answer now, but I do recall that Sisson disagreed with the proposition put by Collinson for two reasons and gave a detailed explanation of why. I think it may have been when he explained that it was because the margin on SEPA was roughly 30% of the margin on Visa transactions.

Collinson recovered well (and even extracted an admission that Sisson was putting forward an opinion), and steered the discussion back to GPTV, but the damage was done - Sisson had managed to make the point that even if you accepted that you substituted SEPA for Visa, if that was lower margin, and it was reasonable to assume that it was, then it was reasonable to assume that the market would consider that as material.

There was debate about whether that was a fact or not, but Sisson then went on to point out that the market operated based on assumptions made by analysts, not facts. I would score that little exchange one all Sisson - Collinson.

But the point you made, in response to @itzgr82balive, about Sisson being cross-examined, stands. He could be cross examined, by Collinson, He was cross-examined. The fact that @itzgr82balive apparently missed that speaks volumes.