“If a serious conflict of interest becomes apparent well before the hearing is due to commence, it seems plain to us that the judge should not sit on the case. This is so whether the judge is a full-time judge or a solicitor deputy or a barrister deputy. On the other hand, if the conflict does not become apparent until very shortly before the hearing or during the hearing, the position may be different. The course the judge or deputy judge should take will depend on all the circumstances. Inflexible rules are best avoided. Plainly, the judge should not sit, no matter what inconvenience to the parties may result, if he doubts his ability to be impartial, but short of that, a number of variable factors will need to be taken into account. What is the nature of the conflict of interest? Are the parties willing for the judge to hear the case? Do they positively want him to hear the case rather than have to suffer an adjournment? Is another judge available to take on the case? If the case has already started, how long has it been going on, and how much is left? What will be the expense consequences for the parties if the judge withdraws? How will it appear to the reasonable onlooker if the judge does not withdraw?”