The 88-year-old, best known for playing Fagin in Lionel Bart's stage and film musical Oliver!, recently took on the guest part of Vincent Mancini for an upcoming episode of the BBC medical drama.
Billed as a "stern old boy with a wicked sense of humour", Vincent is a war veteran who pays a visit to the hospital as he is suffering from a venous leg ulcer above his ankle.
When Chrissie Williams (Tina Hobley) meets Vincent, she manages to offend him by suggesting that the ulcer has been caused by his inability to look after himself.
Eddi McKee (Sarah-Jane Potts) later strikes up a bond with Vincent because she does not patronise him, but she also recognises that he may need more day-to-day care.
With proud Vincent scared of losing his independence, Eddi will have a tough task on her hands as she urges him to consider home help.
Holby City airs Moody's guest appearance on Tuesday, July 17.