An avid coin collector has put the spoils of his searches to good use by donating their worth to a charity close to the hearts of a friend and her late husband.

Dave Richman, from Finchley, was using a metal detector in a field in Radlett, Hertfordshire, to search for historical artefacts when he found a rare gold half-guinea dated from 1788.

It is accepted practice for collectors like Dave to give half the value of their findings to the owner of the field – in this case, his friend Anita Kohn.

Anita insisted Dave keep the £500 the coin was worth, so Dave kept the coin and donated its equivalent value to Myeloma UK, a charity raising awareness for a rare form of cancer.

Eddie, Anita’s husband, suffered with Myeloma and the disease eventually took his life.

Dave, a semi-retired business owner, said: “I go to Anita’s field maybe two or three times every week and, as is the case in most fields, usually only find bottle caps and fairly new coins.

“But this one was worth about two weeks’ wages to the average 18th century worker so it really boggles my mind imagining who might have dropped – in my mind I see some rich person riding a horse.

“I will still be going to the field every week and I hope I can find even more rare trinkets like this so I can donate more money to Myeloma UK.

“It is an awful disease and not enough people know about it so I just hope to do my bit with my metal detector to help.”

Myeloma is a rare and incurable form of cancer which appears in plasma cells, a type of white blood cell made in the bone marrow, and it affects 17,500 people in the UK.

Unlike many cancers, myeloma does not exist as a lump or tumour.

It affects multiple places in the body where bone marrow is normally active in an adult, such as the bones of the spine, skull, pelvis, the rib cage, long bones of the arms and legs and the areas around the shoulders and hips.

Myeloma UK is a charity working to find the cure for the cancer and get patients access to the right treatment at the right time.