David, a war veteran, was very quiet and rarely interacted with his family, much to the concern of Norman, who thought his father didn't like him (Violet felt the same way).
After her death and being made redundant from his job as a lino salesman, he began to hang around with his old school-friends Compo Simmonite (Bill Owen) and Cyril Blamire (Michael Bates).
They divided their time between the local library, pubs, eating at Sid (John Comer) and Ivy's Café and devising adventurous exploits to stave off boredom.
Clegg was a cynic and more critical of the schemes than the others, preferring to take a back seat and casually watch, for example, an antic involving three meat pies; Compo, Cyril and Sid; an alloy spoon and a very angry Ivy (Jane Freeman).
Happy just to read alone in his cosy home, he also finds enjoyment in pondering some of the simpler things in life, such as Sid's skirting board and the price of beer.
He is also so anxious and shy that he wears several layers of clothing: vest/long johns, shirt, jumper/sweater, waistcoat/suit vest, jacket/sport coat, and finally a plastic mac, which he just carries when it's not windy or raining.
This invariably results in a panic attack for Clegg, who fumbles about uncontrollably with the gears and pedals, limiting his speed to about 3 mph (5 km per hour) (which is just to his liking).
From series 9 onwards, Clegg's neighbour Howard (Robert Fyfe) often involved him in his risky schemes to have an affair with Marina (Jean Fergusson) without wife Pearl (Juliette Kaplan) finding out.
After Keith Clifford departed the show following series 27, the quartet became a trio again; however, Clegg's role continued to decrease and most episodes focused on Alvin and Entwistle's schemes.
In the two final series, both Clegg and Truly became official secondary characters, as Sallis and Frank Thornton were now over 85, leading to complications over insurance on location filming, so his role in the trio was filled by Entwistle (Burt Kwouk).