Any damages they decided to award Miss Allan should be 'fair and reasonable', Mr Justice Potts said. 'Bear in mind what you know money can buy in 1992.'
He went on: 'This is, as Miss Allan's counsel has said, an anxious case. It's an important case for the parties. It has attracted much attention but please do not feel over-awed or intimidated by these factors. Juries try cases as important as this, if I may say so, daily - such as cases where the liberty of the subject is concerned. Cases which do not attract the publicity that this case has attracted.'
He urged them not to speculate but to try the case on the 10 days of evidence they had heard.
'Keep your eyes on the central issue. Did Jani Allan have an adulterous affair with Terre-Blanche or did she not? As to this, one thing is certain - somebody has told lies in this court. Your task, using your common sense and knowledge of the world, is to decide what evidence to accept and what to reject.'
Miss Allan, 40, a South African journalist who now lives at Wolsey Court, Hampton Court, Surrey, is suing Channel 4 for damages over the film The Leader, His Driver and the Driver's Wife, which she claims falsely portrayed her as a 'lady of easy virtue' who had an affair with Eugene Terre-Blanche, the leader of the far-right AWB.
Channel 4 says the programme did not suggest an affair but even if it had, the allegation would be justified. The court has heard Linda Shaw, a defence witness who was Miss Allan's former flatmate, say she looked through a keyhole and saw Miss Allan and Mr Terre-Blanche having sexual intercourse.
The judge said that if the jury decided there was a libel, it would have to consider its effect on Miss Allan's position, standing and reputation and the upset, anxiety and embarrassment caused to her.
In deciding how serious a libel it was, the character of Mr Terre-Blanche was a relevant factor.
If jurors found in Miss Allan's favour, they were bound to consider the way the case had been conducted by Channel 4. Mr George Carman QC, for Channel 4, had not been 'mealy- mouthed' and had put his case 'forcefully' to Miss Allan while she was in the witness box.
If the jurors found Channel 4 had failed to justify its central allegation that Miss Allan and Mr Terre-Blanche had an affair but concluded they had a relationship 'falling short of actual sexual intercourse', they could reflect that in any damages award.
The hearing continues today, when the judge will complete his summing-up and the jury will be sent out to consider its verdict.