Wales, for example, has a much higher recycling rate than England. It operates a single recycling system across the country rather than separate systems in every local authority area.

Almost all local authorities in England have kerbside collections of plastic.

But the Environmental Audit Committee heard England had a "particularly high" level of consumption of drinks in single-use plastic bottles outside the home.

So this suggests a deposit scheme could be a good way of increasing recycling in England.

At the moment, more than 95% of the plastic bottles that are processed for recycling have been collected from households.

What about littering?

There's not much evidence to suggest deposit schemes reduce littering.

The Defra-commissioned research said that although "the general assumption appears to be that receiving a monetary or other reward will encourage consumers to deposit containers at a collection point instead of littering", there was little data to support this.

A German study published four years after its deposit scheme was introduced found no evidence of litter reduction.

Who pays?

This varies and depends on the design of the scheme.

In Germany, retailers and the beverage industry have to bear the costs and in return are allowed to keep any unclaimed deposits.

But in other countries the cost is passed on to the consumer.

Several countries with deposit return schemes have a centralised non-profit operating system that runs the collection points and takes back any money from unclaimed deposits.

How much could it cost?

Again, lot of this comes down to how the scheme is designed, so it's too early to put a precise figure on it.

For example, the costs attached to installing a network of "reverse vending machines" will be different to those attached to training existing staff in shops to handle the deposits.

Environmental consultants Eunomia estimated one machine could cost £30,000 to buy, £2,000 to install and another £2,700 a year to operate.