"Approach on appeal
11. By CPR [Civil Procedure Rules] 52.11, as applied by CPR 63.17(1), this appeal is limited to a review of the decision below unless the court considers in an individual case that it would be in the interests of justice to hold a rehearing.
12. ... in those circumstances, before this court interferes with the decision of the Hearing Officer, it should be satisfied that he erred in principle or was clearly wrong.
13. Two factors are present in this case which mean that I should be particularly careful to accord respect to the Hearing Officer's Decision. The first is the warning of Lord Hoffmann in Biogen v Medeva  RPC 1 at page 45 concerning findings of obviousness. He concludes that well-known passage by saying:
"Where the application of a legal standard such as negligence or obviousness involves no question of principle but is simply a matter of degree, an appellate court should be very cautious in differing from the judge's evaluation."
14. Secondly, amongst the factors to be taken into account in deciding the degree of reluctance to be exercised in relation to interfering with such a decision on an appeal, are (a) the standing and specialist experience of the court or tribunal appealed and (b) whether the court or tribunal appealed from heard oral evidence. [citation omitted]
15. The facts of the present case are not complicated. That means that there is a temptation to be drawn in to deciding the case afresh oneself. That is a temptation which needs to be resisted".