David West with onion multipacks at Sainsbury's in Stroud Green Road. Picture: Penelope Diaz

A controversial artist who claimed Jimmy Savile is innocent is taking on his next target – the price of onions.

David West, who staged an exhibition defending the late TV personality at his Islington gallery, has now turned his attentions to vegetables.

He has launched a campaign demanding “realistic prices” for onions after discovering shoppers who buy them pre-packaged at a Sainsbury’s Local store in Stroud Green Road, Finsbury Park, pay three times the cost of loose ones.

He said: “They only sell onions in packs of three for £1.10 at the local store. I noticed how expensive they were last week when I was shopping in the Stroud Green Road branch, so I thought I would try an experiment.

“I bought a pack and then weighed the individual onions at the self-service machine. The price was about 12p each. It’s ridiculous – people are being charged three times as much.”

Mr West, 39, curated an exhibition titled Jimmy Savile Is Innocent, featuring his own works and some by other artists, at his pop-up gallery Bread and Butter in Upper Street in October.

He insists Savile has been unfairly treated and that most of the allegations against him are fabricated.

The exhibition was condemned by ChildLine founder Esther Rantzen, who also dismissed Mr West’s idea of staging a “posthumous trial”.

However, his call for cheaper onions could gather greater support.

After lodging a complaint with Sainsbury’s, Mr West formed a campaign group on social network Facebook in which he accuses the supermarket of “not knowing its onions”.

It links to a video of his experiment, which clearly shows an onion from a £1.10 three-pack being priced at 12p when weighed by a self-service till. He added: “They are exploiting innocent customers by causing them to buy more onions than they need and charging them excessive amounts.

“People think if you buy in bulk, you get cheaper items, but that’s a lie. They should go back to selling them loose.”

A spokesman for Sainsbury’s said: “We follow strict government legislation on the labelling of our food products. We recognise however that this can be difficult for some customers to understand so we’ve been working hard to prevent any confusion.

‘‘For example, we have recently introduced a per-item price on bananas so customers can make an informed choice about what to buy.”