In another, Currys is said to have listed a Samsung television for £579 “was £699”. “The Black Friday price of £579 for this Samsung television was only slightly less than the price it was going for just days before Black Friday – £599,” Which? said. “It had been sold at £599 for months, making Currys’ decision to use a ‘was price’ of £699 both mystifying and, in our opinion, misleading.” Last night, Pete Moorey, head of campaigns at Which?, said: “Shoppers might be surprised to learn that only half of Black Friday deals are actually cheapest on Black Friday. Half of electrical goods sold on Black Friday are cheaper at other times of year, an investigation by Which? has found.Forty-nine per cent of products “on offer” cost less in the months before or after the annual bargain frenzy, the consumer watchdog said. We fundamentally disagree with this approach taken by Which? in this reportCurrys Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. More expensive products included a 48-inch flatscreen Samsung television from Currys, advertised as £698 on Black Friday but dropping to £599 just weeks later in December, and a Vax Air Classic Pet on AO.com, which had been £30 cheaper the day before.In recent years, Black Friday has become the biggest shopping day of the year with companies promoting apparent cut-price and limited-time bargains for customers to snap up before Christmas. The investigation tracked deals on 20 popular gadgets and appliances on Amazon, AO.com, Argos, Currys and John Lewis for three months before and two months after Black Friday last year.It found that just 8 per cent of discounts were one-day only offers. Meanwhile, 12 per cent were cheaper at some point in the three months before and 38 per cent cost less in the weeks after. “If you’re thinking about starting your Christmas shopping around Black Friday, do your research as some ‘deals’ may not be all they’re cracked up to be.”Which? also accused AO and Currys of breaking government guidelines after it appeared to uncover examples of offers where the word “was” had been used to make deals appear better than they were. A spokesman for Currys insisted its prices were “transparent”.“We fundamentally disagree with this approach taken by Which? in this report and comply fully with the PPG guidelines, displaying a clear date from when the ‘was’ price was taken,” she said.AO said that some products remained on promotion beyond Black Friday to give customers “great deals beyond just the one day a year”. AO said it had followed regulations when it came to displaying discounts. Shoppers might be surprised to learn that only half of Black Friday deals are actually cheapest on Black FridayPete Moorey, head of campaigns at Which? A John Lewis spokeswoman attributed its prices to its ‘Never Knowingly Undersold’ promise, and said: “Our never knowingly undersold commitment means that we will match our competitors’ deals and offers for as long as they run.”Argos said: “We offer customers thousands of great deals over the Black Friday period and work hard to ensure that all of our offers are fully compliant with the full range of regulations and guidance in pricing practice.”We certainly do not intend to mislead in anyway. We update our pricing frequently to ensure that we can offer our customers the best deals.”A spokesman for Amazon added: “Six of the eight products that Which? reviewed on Amazon.co.uk last year had our lowest price on Black Friday and, in response to customer feedback, we spread out great deals over several days.” Some are up to £99 more expensive on Black Friday, prompting Which? to warn customers that deals are not always what “they’re cracked up to be”. The Government’s Pricing Practices Guide (PPG) states that product comparisons should “in general” be made with the immediate previous price for the product. If this cannot be done, the basis of the comparison must be “explicit”.Which? highlighted several examples of places where it believes the guidelines were breached. It says a “was” price must be the most recent price the item was sold at for 28 consecutive days or more and not a price that is more than six months old.In one case, it said AO listed a Bosch washing machine for £399 “was £539” – the price it had been for 19 days the previous year instead of the £499 it was in the months before.