QBD 28 June 1994. In the course of a rent review arbitration the plaintiff landlord`s expert, M, gave evidence on the changes in the office market in relation to the review date. He was cross examined concerning evidence he had given at two previous arbitrations. Following that the respondent issued two subpoenas, one to M to produce his proofs in these previous cases and one to J, thier own expert, who had also acted in one of those arbitrations. M and the plaintiff applied to set aside the subpoena on the grounds that the proofs were confidential. The plaintiffs summons was dismissed and that of M but the summons to set aside the subpeona against J was allowed. It was held that if a witness were prooved to have expressed himself in a materially different sense when acting for different sides, that would be a factor which should be brought out in the interests of individual litigants involved and the public interest.