A Hampstead art school displays some of Errol Jackson’s 25,000 candid images of sculptor Henry Moore hard at work.

Henry Moore liked to work every day. “Only if work is unending is life endurable” was his motto.

He also liked to have his work and himself photographed: his hands, processes, studios, maquettes and inspirational objects. From 1961 until his death in 1986, he employed Errol Jackson as his personal photographer, resulting in over 25,000 images.

Jackson was a scientist who had learnt to take, develop and print photographs by the age of seven. He was married to the artist Jeanette Jackson, co-founder of the Hampstead School of Art (HSoA), of which Moore was a patron. The school’s gallery currently has a selection of Jackson’s images of Moore, who lived in Belsize Park for more than a decade, coming to Parkhill Road in 1929 and moving to the Mall Studios in 1940. Within months these were bombed and he settled in Perry Green in Hertfordshire.

Errol met him through photographing an exhibition pairing Jeanette’s paintings with sculptures by Isaak Witkin, then Moore’s assistant. Moore asked him to capture how certain things happen in his own sculptures, including cavities which he referred to as “caves in cliffs”. He also wanted photographs of the sculptures in the round, revealing different aspects of the same concept.

But Jackson’s relationship with Moore went further than these requests. According to critic Estelle Lovatt, who carried out research at the photographer’s archive for her book Henry Moore at Work, Jackson observed the sculptor “like an animal in its habitat”, aiming to be present but forgotten.

She attributes the lively variety of expression on Moore’s face to their agreement that he should never pose for the camera. However, Moore did stipulate certain conditions – he banned shots of himself working in a jacket and tie, rather than the butcher’s apron over a cardigan he habitually wore, and also of the glasses he wore for close work as Moore thought these a sure sign of ageing.

At Perry Green, Moore had several studios but spent most time in the one where he made maquettes, a former village shop. Jackson’s photographs show its old fashioned coke stove, a multiplicity of traditional and modern tools and an array of starting points for sculptures ranging from a sheep’s skull to a Brussels sprout stalk. He also captured a scene there where Moore is making plasticine models with his young grandson - elephants, crocodiles and sea lions for an ark.

Although his work was much sought after by architects, Moore felt buildings absorbed or clashed with his sculptures so preferred to have them photographed in landscapes in natural light. Broken clouds were the most desirable sky background, giving a 3-D effect to sculptures. He liked them to be photographed from all angles with a camera level with the base to emphasise monumentality.

Puddles were a problem as they reflected upwards over the piece, changing the surface appearance. Jackson’s family sometimes played a part – as bird scarers to ensure there were no droppings on sculptures cleaned up for photographs but awaiting the perfect moment for taking pictures.

Moore explained his predilection for natural settings and forms in the film Henry Moore and Landscape, showing his sculptures at the Yorkshire Sculpture Park. I made a subtitled version of his narration, including autobiographical reminiscences, for the Henry Moore Foundation. I will be showing this, along with my subtitled version of a 1968 film about Barbara Hepworth in Cornwall, at HSoA next Thursday (March 17) at 6.30pm.

Henry Moore at Work runs until March 24 at 19-21 Kidderpore Avenue NW3, Tuesday to Thursday 9am to 8.30pm, Friday noon to 5pm, Saturday 9am to 5pm. Films free but booking essential: info@hsoa.co.uk. 020 7794 1439 or visit website.