“Security,” evidently engineered by South Africa, had expelled me from Zambia in 1970 and was now doing the same in Botswana. I would go to New Zealand, but had no idea when I would see Africa, let alone “home” again. And wife, Barbara, not having any outstanding legal issues and holding an Irish passport, was ensconced, along with our daughter, with her parents in a Johannesburg apartment.

The week before Christmas, Barbara phoned to tell me that, belatedly, our daughter had started walking. I decided I could make it safely to Johannesburg to see Ceiren walk. All it would require would be a degree of subterfuge and some disguise: it would be my Christmas present to myself.

I told Barbara – and anyone else I could – that I would take what might be my last chance to travel through the Okavango Delta. I would be away, and out of touch, for three weeks. Then I bought some black hair dye at a local pharmacy and, on a different day from a different assistant, a pair of heavy-rimmed spectacles containing plain glass. Back at the hotel, in the evening of 23 December 1970, I dyed my hair, beard and moustache black, then shaved the middle out of my goatee beard to give me a drooping “Zapata” moustache. The finishing touch was a grey fedora hat.

That night, near to midnight, I made my way on foot through the bush, skirted the Botswana and South African border posts and then started a six-hour run roughly parallel with the road to Zeerust. This I did at a “scout trot”: 50m running, 50m walking.

After about two hours, I realised I had made a major mistake: I was wearing woollen trousers and these chafed the insides of my thighs. But they were the only trousers I had. Inside the briefcase I carried were changes of underwear, socks, shirts and a tie. So I took off my trousers, looped them over my neck, and continued in my underwear.

With the sun showing signs of rising and estimating that I must have covered at least 25km, I pulled on my trousers, tied on the tie and walked along the road. I soon found myself heading to Johannesburg, sitting beside a charming man, a lawyer. He was on his way home to the suburban outskirts of Johannesburg having handled a court case in Gaborone.

Adopting what I imagined was a mildly inflected London accent, I told him I had spent years in London and was now paying a surprise visit to my family in the central city flatland of Berea. It was my lucky day, he said. I should join his family for lunch because, after lunch, he would be driving across the city to visit friends.

I easily slipped into the role of the returning exile, able to regale the lawyer, his wife and children with true-enough insights into life and times in London. And when I waved off the family as I stood, for the first time in years, on the pavement two blocks up from Park Station, I was completely relaxed. My new persona was accepted. I even had a name: Andrew Marsden.

But then it all fell apart. As I strolled confidently down Rissik Street toward the station, I was convinced I saw people I recognised. Panic struck. I forgot I was disguised, convinced I would be recognised. So I took the first taxi I saw and was dropped off in the early afternoon of 24 December outside Berea Towers in Abel Road.

As I paid off the cab, I looked around furtively: the immediate vicinity was deserted. There was also no one in the hall of the block of flats as I stepped into the lift and pressed the button for the ninth floor. That too was deserted. So far, so good, but when I rapped on the frosted glass door of number 93 at the end of the corridor, there was no response. I knocked again, rather more stridently. Nothing. They would obviously be back. But when? And what was I to do in the meantime?

So it was, after two brief and nervous sojourns on a bench in a nearby park, pretending to read a newspaper, I ended up behind the door of the cubicle that housed the ninth-floor garbage chute. With the door slightly ajar, I could look down the length of the corridor to number 93. Seconds transformed into minutes and minutes into hours as I watched and waited.

Finally, there were footsteps. Barbara and her family coming home? Or, if it was someone coming to throw garbage down the chute, I would pretend to have just done so myself, and leave. But the footsteps passed by the door: it was Hunter and Pat Robertson, the Scottish electrician and his wife from Zambia who had promised to visit Barbara’s parents when next they were in Johannesburg.

As they knocked on the door at the end of the corridor, I stepped out from the garbage cubicle and walked toward them as they turned and walked back. Hunter, a large muscular man, glowered at me as I blocked their way. My cue: I doffed my hat with one hand, whipped off my glasses with the other and uttered a loud “Tah-Rah!”

When they had recovered, both Hunter and Pat insisted the disguise was perfect. Nobody would be able to recognise me. And, said Hunter, since Barbara, Ceiren and the family were obviously out shopping and would only be back later, why didn’t he and Pat take me on a tour of “your old haunts”.

It was early evening before we returned to Berea Towers, where Hunter and Pat, sworn to secrecy, ushered me into number 93 as a “surprise present”. It was an incredible moment. And Ceiren, tottering on her feet and hanging on to Barbara’s leg, seemed oblivious to any disguise. “Dad,” she said, with one word putting paid to the Robertson’s assurances about my disguise.

But it was obvious that there was no way in or out of the apartment other than the frosted glass door leading to the corridor. However, there was a bathroom window that gave access to an apparently very secure sewage pipe that ran from the bottom to the top of the building. If necessary, it would be possible to get out of the window and use the pipe to climb up to the roof of the apartment block.

Crazy as it may seem, the discovery of a putative escape route enabled me to relax as I waited for the arrival of my father-in-law. I was unsure how Rex Edmunds would treat me. He was certainly no liberal and had a reputation as a hard man, but I needn’t have worried.

After Rex had recovered from what was obviously an initial shock, he made it clear that he admired what I had done. I had proved that I had guts and really loved his daughter and granddaughter. It was drinks all round and happy families when, suddenly, there was a knock at the door. Through the frosted glass panels it was obvious that there were at least two people, their caps denoting uniforms.

I bolted for the toilet and launched myself onto the window ledge, gripping onto the cast-iron pipe that was my flight path. Rex, who had a few very strong dislikes, confronted one of them when he opened the front door: Salvation Army carol singers. He had promised never to “give a penny” to the “Sallies”, but he promptly pulled out his wallet, handed over a banknote, and wished them a merry Christmas.

From my perch on the window ledge I saw the would-be carol singers depart. I felt weak with relief as I hauled myself back into the flat and walked up to the living room to face Rex. He looked straight at me and announced: “You’re not going out. You must not leave this flat.” I nodded agreement and we sat down to have, what I now realise, was a badly needed drink.

However, it all turned into a quietly grand Christmas Day. There were no knocks at the door, Jean cooked and Barbara, Ceiren and I spent most of the time playing on the floor, reading, laughing, eating and relaxing.

But then it was time to leave. I had decided to catch a train in the afternoon that arrived in Mafeking (Mahikeng) near the border at 8pm. I would then disembark, head north away from the town, and then due west and cross the border. I must have sounded well prepared, because Rex never asked me if I had a map or had consulted one.

But I didn’t have one – and nor had I looked at one. Had I done so, I might have realised that Mahikeng lies southeast of where the north-south border turns west; that by running westwards, I would simply be running parallel with the border. DM