The journey to Bensham Manor School is not a particularly cheery one. It is a red-brick Victorian building situated in Ecclestone Road, a not particularly outstanding or memorable part of the oasis in South London that is Thornton Heath, surrounded by streets formed by houses that bear the air of an inevitable decay, so that whilst many of the householders were attempting to make the best of their castles – lawns kept mowed, flower-beds weeded, garden gnomes aplenty – there were too many that were empty and boarded up, or in a state of serious disrepair, and most of the public green spaces were ill-kept and tatty. I knew the area quite well because many of the people living there were my patients, and I knew, too, that many of these people were decent and honourable, the whole environment spoiled by a small but significant minority of undesirables. To Max, though, it was all new. Coming from an upper-middle-class background (both parents were senior doctors, she was a trained vet), areas such as this one were as alien and scary as the dark side of the moon, and I suspect she had eyes only for the less seamy views around, was blind to the positives. She kept looking around her with widened eyes and mouth ever so slightly open, as if she had heard of such places, but had never before quite believed in them.

It was somehow worse because it was hot. My God, was it hot; it seemed to have been hot for years now. The whole world now seemed desiccated and dusty, the only moisture a sort of greasy film adhering to every surface, tainting every memory.

The campus of Bensham Manor School (although that word had yet to find its way into the British English language, as we must call it) was not itself, at least at a distance, harsh on the eye. There was a three-storey main school building in red brick, a very Victorian affair but none the worse for that. In front of this was a large playground, to the right of which was a more modern two-storey building attached by an annexe to the original edifice. To the left were some single-storey 'temporary' classrooms ('temporary' as in not made of brick or stone, but going to have to last a long time anyway), whilst behind was another playground bounded by a science block, an arts centre and a gymnasium. A lot of the bare surfaces were decorated in graffiti which, to my aged eye, did nothing to make it a more pleasant environment. We were going there because it was the school's summer parents' evening; it was late July 1977, and the weather was hot.

Perhaps at this point, lest you be leaping, nay bounding, to unwarranted conclusions, neither I nor Max, either singly or in combination, was a parent of anyone attending Bensham Manor School in Thornton Heath, Surrey. Indeed, quite the reverse; we were going to see my parent, Benjamin Elliot. For those of you not familiar with my progenitor in this vale of tears that is modern existence, let me explain some things. I am a general practitioner in the fair burgh of Thornton Heath, which itself lies to the south of Streatham and north of Croydon; it is positioned on the Brighton Road, which is nice because it means that once a year the London to Brighton Old Crocks race passes through – always a treat for the entertainment-starved locals. Max, as I have said, is a vet, also residing and living in Thornton Heath, and I am lucky enough to have found that she rather likes me; my father is a retired GP, dedicated gardener and allotmenteer, and just – but only just – sane enough to have escaped permanent incarceration in a padded cell.

The reason this reprobate was present at the school that evening was because he had spent the last six months running a Horticultural Club there. This had been the idea of the headmaster, Mr Silsby, as a way of teaching some of his more troublesome pupils (he preferred the term 'high-spirited', but we all knew what he meant) some useful skills, and Dad had got the gig because he was friendly with Mrs Ada Clarke, and Mrs Ada Clarke was the head dinner lady at the school. She had heard talk of Mr Silsby's new, pet project, and had rushed to propose Elliot Senior as a potentially useful volunteer. Dad, in turn, with his customary enthusiasm for striking out in different directions whenever he could, had jumped at the chance.

'I wonder what she looks like?' asked Max. Neither of us had ever met Ada, although we had heard plenty about her. She was in her early sixties, was a good Christian woman with a penchant for bell-ringing (which she did at St Jude's Church on Thornton Road) and was, according to Dad, a real 'stunner'. From my perspective, this meant nothing; since he had become a widower some decades before, he had sought the attentions of a startling variety of womanly types – Margaret Wallcroft (who had a glass eye and a vocabulary that would have made many a hardened navvy feel faint), Annie Mallett (a very pretty, petite woman who spoke in a high-pitched lisp and giggled with such irritating regularity that an evening in her presence had left me a gibbering wreck) and Nanette LaRoche (who was French and sophisticated, played the bagpipes – I kid you not – and did so badly) to name but three. Dad had been seeing Ada for eight months now and tonight was to be the night that we would finally be allowed to cast eyes on what he assured us was pulchritudinous perfection.

'Well, on the whole, he tends to go for reasonably attractive women – although I had my doubts about Margaret, especially when she tripped on the stairs and her eye fell out – but it's the personality you've got to worry about. Like attracts like, so that, generally speaking, he only goes shopping for life companions at the fruitcake stall.'

'That's not fair. Your dad's not a fruitcake. He's just ...' She hesitated, groping for some words that might encapsulate my father's propensities for extreme eccentricity but that did not go so far as to say he was a total, eye-rolling, frothing-at-the-mouth maniac. 'His own man.'

Well, as an epitaph, it sounded pretty good, but as an excuse it left a lot to be desired. I murmured, 'At least Ada doesn't sound as though she eats insects and sleeps hanging upside down in the understairs cupboard.' In fact, during Dad's little problems with his neighbour (Oliver Lightoller, who had once been at perpetual war with Dad), Ada had refused to join in with my father's lunatic schemes, something that had temporarily put a dampener on the relationship; clearly, though, love conquer'd all.

'She sounds as if she is a very fine and upstanding woman,' said Max.

'So what does she see in Dad?'

'You're being unfair; your father's a thoroughly decent man.'

'Seven months ago he spent two nights in a police cell, accused first of arson and then of murder. That kind of thing doesn't usually happen to "thoroughly decent" men.'

'He was innocent,' she reminded me, with more than a touch of scolding in her voice.

We had reached the gates of the school. There was a man in a red nylon tabard telling the world that he was a steward; he was short and portly, and had a moustache. He also wore rounded, NHS glasses. I knew the sort; the soubriquet 'steward' is actually code for 'little Hitler'.

'Over there,' he said, indicating a field to our left where the cars seemed to stretch to a heat-shimmered horizon that could easily have been Land's End. It wasn't so much the words as the tone that started me...