Last year Mark's work chosen was for the Royal Society's annual exhibition out of more than 1,500 entries.
This year, during lockdown he's been taking part in the #PortraitsForNHSHeroes initiative created by fellow Oxford Art Society member and painter Tom Croft.
Mark shot to fame after he painted a portrait of himself everyday as he underwent gruelling chemotherapy for blood cancer.
Mark said: "When I found out about the project I thought what a great idea and lovely way to give something back to the NHS for all amazing work they are doing during these very strange and difficult times.
"Also on a personal level I’m very grateful to the NHS after receiving treatment for a blood cancer in 2018."
You can read more about the portraits for NHS heroes project by clicking here. Mark painted Megan, who works as a nurse at Chelsea and Westminster hospital in London.
Megan was brought up in Brill.
She has only been nursing for a year and a half, and she was transferred to the ITU unit during the Coronavirus pandemic, in what has proven to be a baptism of fire.
Megan said: "I felt very lucky that I had worked in a medical ward and had recent surgical experience before being transferred to ITU during the Coronavirus pandemic as both areas intertwined in the high level of care- but was still surprised by how different it felt to any experiences I’ve had through training and qualification.
"As someone who enjoys chatting with patients it felt very strange to be looking after someone and not know what their voice sounded like.
"The dissonant sound of countless beeps, hums and drones from the equipment in the room almost became the patients voice whilst they couldn’t use their own- alerting to when something is wrong and reassuring when things improve.
"My overwhelming feeling of working in ITU during the pandemic was gratitude for the nurses, doctors, physiotherapists and other fantastic members of the healthcare team.
"I continually saw colleagues support each other and help with not only the patient during and incredibly scary and difficult period of their life, but also fortifying and providing reassurance to ITU newcomers like myself.
"I’m grateful for my ITU experience, and feel very lucky to have seen so many patients improve and to use their voices again. “