In 2007, I left the NHS after 41 years, having spent 23 years as a GP in an affluent part of north Leeds and 10 years as professor of primary care, practising in poorer areas of south Leeds. I was healthy, fit, comfortable and pensioned. I was looking for a new challenge.
I had in the past applied to volunteer with international development charity VSO (Voluntary Service Overseas), but it rejected me. This was a good decision; I was 22 and immature. Four decades later, I had the skills and the experience required. I reapplied and this time, I was accepted.
After preparation in the UK and two months of initial training in Cambodia, I was working in the capital, Phnom Penh, where I remained, on and off, for four years. I was placed in a local non-governmental organisation to advise on maternal and child health.
Reducing maternal deaths
Among scores of maternal and child health advisers in Cambodia, I was the only one with a community background, surrounded by hospital obstetricians and midwives.
The first 18 months were full-time. Thereafter, I spent four out of every 10 weeks in Cambodia. I became completely committed to reducing the horrific levels of maternal death worldwide.
Two years ago, VSO circulated a web link to Charity Challenge, an organisation that runs more than 100 expeditions each year to support charities. I wanted to raise money this way for VSO, if I could find something I would enjoy. The website listed treks, bike rides, mountain climbs, rafting, sky-diving, dog- sledding and ski challenges in more than 30 different countries.
As soon as I saw the trip to the North Pole, I knew it was for me. As a boy, I read stories in comics of adventurers attempting to reach the Poles. I immediately contacted Charity Challenge, telling it that I was fit but would soon be approaching the age of 70.
I run six to eight miles twice a week, eat healthily and seem to have avoided the diseases of ageing (so far).
I have also been cross-country skiing most years since I was 50, having decided then that I was too old for downhill skiing.
Fortunately, Charity Challenge was unconcerned about my age, saying that if my GP deemed me fit for the challenge, it would take me.
Our North Pole team is a group of four. The leader, Al, is a very experienced polar explorer. The other two are, like me, polar novices.
We met in November for a training weekend, dragging car tyres on Dartmoor, and rapidly became a mutually supportive team.
I shall next meet the other two in Heathrow when we fly out on 31 March. We will then meet Al in Svalbard, Norway, where he is completing preparations.
After two to three days of snow training in Svalbard, we fly to Camp Barneo - a temporary camp erected each year by the Russians about 150 miles from the Pole.
Our mode of travel over the ice is called ski trekking because we wear broad skis with sealskin stuck to the bottom; this makes them smooth in one direction, to glide forwards, and rough in the other, to prevent sliding backwards.
We will drag 60kg sledges loaded with everything we need - tents, clothing, food and fuel. We are prepared for temperatures that could sink to -45 degsC, even before wind-chill is taken into account.
The terrain is mainly flat, until we reach the junction between the ice sheets. Here we may encounter huge pressure ridges one to five metres high, over which we must manoeuvre our sledges.
We might also confront seawater gaps between the ice flows, which may require us to build ice bridges. There is even a risk of meeting polar bears.
I shall stretch myself physically and psychologically, but I intend to have fun; it is my retirement treat to myself. I am paying my own costs for the expedition, so all money raised goes straight to VSO.
Having invested so much in the challenge, I felt I should raise a suitably substantial sum for VSO, so I set my target at £30,000. Raising this has felt at least as unfamiliar and intimidating as the trek itself. But I am now half way to my target.
We return on 13 April. Six weeks later I turn 70 and I've planned the biggest party I've ever had for family and friends. I have a feeling I shall have earned it.