He was elected to the position unopposed in June last year on a platform of strengthening landscape in the public sector and pushing for statutory landscape status in development regulations. But just as he took office the UK voted to leave the EU, so Brexit will now be at the forefront of his work over the two-year term.
Denton-Thompson is no stranger to policy fights. He has been involved in Government policy over his career, from stimulating the first Countryside Stewardship scheme to directing the Countryside Character Assessment programme. He was assistant director of environment at Hampshire County Council and has taken the Department for Transport to the European court for its failure to comply with European environmental law.
He is ready for a battle should the Government try to use Brexit to undo environmental controls. "We must not allow politicians to think the nation voted to exit Europe to dismantle environmental legislation," he said. "That is uppermost in my mind. Over my dead body will any environmental legislation be weakened in any way because that's not what the public wants."
However, he is excited about the chances Brexit offers to develop a new vision for landscape and the countryside, replacing tired EU agricultural policy and modernising a green belt policy that is "past its use-by date".
The 20th-century saw hedgerows and woodlands removed, wetlands drained, flower-rich pasture ploughed up and mixed farming disappear as guaranteed market prices removed risk from the monoculture model. But farming is now on its knees, said Denton-Thompson. "We now have an almost unsustainable food-production system. It's heavily reliant on chemicals and mechanisation of the landscape at the expense of our soils, which are depleted of biodiversity."
The sector is ripe for a move towards proper sustainability, he added, and the landscape sector can drive that change. Through Defra's 25-year plan the Landscape Institute is pushing for the department to think on a "sub-national" landscape scale, with farmers providing a raft of ecosystem services such as catchment management.
A more sustainable, biodiverse and even organic approach to farming is also on the cards, he suggested. Farms will produce more horticultural produce, from fruit and vegetables to nuts, with a reduction in animal farming for reasons of diet and climate change.
Changing farmers' behaviour should not be on a regulatory basis but through a contractual relationship where farmers collaborate with the Government to deliver additional goods, he said.
That approach will filter through to the entire horticultural sector, which will move towards providing ecosystem services, especially in places such as parks and school grounds, Denton-Thompson explained. He founded Learning through Landscapes, which focuses on school landscapes to improve children's behaviour and learning.
"Horticulture as a profession can do more for children and young people than any other profession, especially in the current circumstances," he said. "For a far too high percentage of children, the only access to open space they have is the school playing field - and that is under threat. It should be one of the most exciting rich environments anywhere in the public or private sector but it is among the most sterile."
Everything from play to reading and social interaction is improved by horticulture and well-designed landscapes, he added. "We've really got to revalue our green spaces and reposition the important contribution that access to green space makes to health and well-being.
"I'm very keen to work with the horticulture industry to make the case for a new statutory obligation on local government to provide and manage parks. It could be an uphill battle but I would say there are very good long-term financial benefits. It's at a high risk that we remove access to green spaces.
"We've got to look at prevention and tackling the needs of health and well-being - reconnecting people with food growing, reconnecting children with natural systems and creating social stability by designing open space to meet the needs of society."
Collaboration across the sector will be key, he pointed out. "We need to pull together in a coherent and strong message and get society behind us. As a consequence, the politicians will follow."