‘And we’ll run a project, or a centre of interest, based on the lecture,’ said Miss Hughes, grinning. ‘Such things have been filmed before now for so-called educational purposes. So that’s that. It will do the poor things all the good in the world to chase about over the hills and imbibe the fresh air and plot out the lie of the land. And they won’t miss much, I can assure you. By the way, one of them, Miss Golightly, is an ex-policewoman. Would you consider telling her in confidence what you’re after? I take it that you suspect murder?’

‘I don’t think we had better tell her that. It might be embarrassing for her to be compelled to keep silence, and I don’t think it would help us much to have her know the real point of the project.’

‘Right. I’ll put everything in train. But you do think the poor woman was murdered?’

‘That is not an admissible question, but, in your private ear, yes, I am pretty sure of it.’

‘Bets have been made in the Common Room, I believe. We have remarked on your continued presence in the neighbourhood, and have come to the closely reasoned conclusion that it is not for nothing. By the way, I take it that there is little likelihood of the students’ finding anything gruesome?’

‘Oh, I’m sure they won’t.’

‘Good. Then I’ll put in a memo, and send you an official invitation to lecture.’

The next day Mrs Bradley received this formal invitation and she answered it by return of post, giving the written answer, in fact, to Sidney Blott in person when he delivered Miss Hughes’ official letter.

The lecture itself was a great success. Mrs Bradley had been pulling her nephew’s leg when she had announced her subject. What she did lecture on was the use of a theodolite in surveying, and what she demonstrated was the construction of a home-made one which could be guaranteed to function. The students (‘poor brutes’ as Deborah observed) were interested in anything which they thought they could pass to the children in their classes later on, and they fell for the home-made theodolite with a zest which warmed Mrs Bradley’s heart although it burnt a hole in her conscience.

A second lecture saw the amateur surveyors well on the way to the completion of their instrument, and, the weather turning suddenly spring-like, Miss Hughes altered her time-table sufficiently to give the students a chance to wander off in groups and couples into the hills to test their new toy and tabulate the results.