"Ultimately, I am not asked to, and do not need to, decide whether any of the above means there is no jurisdiction to add part 20 defendants to arbitration claims, and I therefore do not do so. I do, however, have considerable doubts as to whether there is jurisdiction to add defendants to, or permit part 20 proceedings in respect of, a part 8 arbitration claim, and I think it right to flag the issue as one which may arise for determination in another case. I note that HH Judge Pelling QC expressed a similar skepticism."