Online shopping can help consumers to stick to their Christmas budgets because it makes it easier to find the cheapest deals, according to a new report.

Voucher site Save.co.uk said a recent poll by YouGov found that 18 per cent of Britons fail to stay below their spending limit when buying gifts for their nearest and dearest.

To test this, it gave twins Kellee and Ryan Ashlee identical budgets and three hours in which to purchase five presents. Kellee hit the high street, while Ryan used online shopping sites.

Kellee ended up one hour and £17 over her allocation.

She said that her task had been hard because she could not compare prices for different items online.

"I tried to make some savings but it was difficult," Ms Ashlee added.

Ryan, meanwhile, completed his part of the challenge in two-and-a-half hours, with £20 to spare.

He said using websites to find discounts on the items he was after had cut down his shopping around time, while also taking him to sites he would not have thought of using.

According to the Interactive Media in Retail Group, over half of British adults will buy some of their Christmas gifts online this year, spending a total of £6.4 billion in December alone.