Director of Conservation, Andy Lester has been speaking to Premier as English shoppers face a 5p charge from today as part of a Government scheme to reduce litter and protect wildlife.
Welcoming the news, he said: "Any scheme that reduces plastic bag use at the surface is good news."
But responding to whether the change went far enough, he said: "Absolutely...I think it needs to be all or nothing. The best way to get people saving on carrier bags is to buy biodegradable ones or bags that last and then there's an outright ban.
"Why do we need a plastic bag for carrying medicines home in? Or for carrying flowers? It makes no sense at all. All products should be treated the same way."
Under the new changes, retailers with 250 or more full-time equivalent employees will be forced to charge a minimum of 5p for the bags they provide for shopping in stores and for deliveries, but smaller shops and paper bags are not included.
Critics claim it may not be as successful as other UK countries where all bags cost. In Wales the number of bags handed out by retailers fell by 79% in the first three years.
The Government expects the scheme to reduce use of single-use carrier bags by up to 80% in supermarkets, and 50% on the high street.
It is also expected to save £60 million in litter clean-up costs and generate £730 million for good causes.
Chancellor George Osborne has confessed to being a user of single-use plastic bags, and suggested he would pay the 5p charge rather than change his habits.
He told Sky News: "I'm ashamed to admit I'm a plastic bag user, and I'm glad I've had this opportunity to make that confession on your programme. But now I will be charged for it."
But Andy Lester expects the vast majority to change their ways. "It will make a difference," he said. "If you imagine an average food shop - you may use 10 carrier bags and that's a saving of 50p. Once the fee comes into place you'll be getting annoyed by the small amounts [you have to pay]."
In England, 7.6 billion single use bags were handed out by major supermarkets last year. That's the equivalent of 140 per person and 61,000 tonnes in total.
Listen to Andy Lester speaking to Premier's Marcus Jones on the News Hour: