When and why did you start running, and what races have you run so far?
When I was 35, a prefect at the school I taught in suggested that we organise a 10-mile run for the staff and pupils. I agreed reluctantly as I had never enjoyed running, but I did quite well and beat a lot of people that I thought were faster than me. Running then became my main sport. I took part in lots of races and, in 1985, ran the London Marathon in 3:05. I ran it three more times then decided to have one last attempt in 2013, a week after my 70th birthday. I enjoyed it so much that, as I crossed the finish line, I decided to do it again. The same thing has happened every year since then.

What do you enjoy most about running?
I have always been a poor sprinter, but have good stamina and endurance and quite a high pain threshold. I enjoy the feeling of physical tiredness at the end of a run. I enjoy almost anything in the fresh air, and have a good tolerance of cold, heat, wind, rain and snow. Virtually all the runners I know are really nice people, whose company I enjoy.

What marathon are you running, why did you choose it, and what time are you hoping for?
I am running the London Marathon for which I have a ‘Good For Age’ place. This is for the ninth time and the fifth since I turned 70. London is the only marathon I have run. I wish I had done others when I was younger and faster. I love the course and the crowds and its prestige. Richard House Children’s Hospice is such a good cause and I like being one of the 25 or so people who run for it. I hope to finish in under four hours – even a second under would be great.

Why did you want to be part of the Big Marathon Challenge?
I feel that under four hours is not unrealistic – in spite of getting slower with age – if I have the extra help and incentive the challenge provides. My fastest time since turning 70 is 4:03. The following year, I almost made four hours, but got cramp in both calves at mile 21, and only managed 4:16. I have enjoyed reading about previous participants in the Challenge, envying them and in a way willing them on to achieve their aims as if I knew them.

Tell us one interesting fact about you.
I think I have had an active and interesting retirement for 13 years. I regularly go running, kayaking, sailing, walking and scrambling in the mountains. I do some voluntary work and I paint. I have also skied across the Greenland ice cap, climbed to 7,000 metres up Mt Aconcagua in Argentina, backpacked the John Muir Trail in California and been horse trekking in Mongolia.