Just one in 20 so-called Black Friday “deals” are cheaper during the shopping bonanza than at other times of the year, an investigation from Which? has found.

Ahead of this year’s Black Friday on November 29, the consumer group said it had found “few genuine discounts” after monitoring sales pricing around the event last year.

It tracked the prices of 83 products on sale on Black Friday last year – starting from six months before the day itself to six months afterwards.

The consumer champion looked at deals from retailers including Currys PC World, Amazon and John Lewis, and claimed it had found just four (5%) products that were cheaper on Black Friday than at other times of the year.

Which? found that six in 10 (61%) of the products on offer – which included speakers, soundbars and kitchen appliances – were cheaper or the same price on at least one day in the six months before the annual sales event in November last year.

When looking at the two-week period surrounding Black Friday itself – including sales prices in the week before and after – Which? found that three quarters (74%) of products were cheaper or the same price in the six months after.

While Which? did not find evidence that any of the retailers were breaking the law, the consumer champion is concerned that shoppers are at risk of being confused by Black Friday offers that might not be as good as they sound.

It is urging shoppers to not get carried away by the hype of Black Friday sales and to do their research to assess whether the price and quality of the product they are considering makes it the right deal for them.

Examples of Black Friday “deals” Which? found include:

– A Samsung HW-MS650 soundbar was £299 at Currys PC World on Black Friday, but within a month the price dropped by £49 for at least five days. Which? found it was priced at £279.97 at least 13 times in the six months after Black Friday.

– A DeLonghi Autentica Cappucino Bean-to-Cup coffee machine was priced at £399 by John Lewis on Black Friday. It was cheaper on at least 64 days in the six months after, including being priced at £368 on at least 35 occasions.

– An Indesit IDC8T3B tumble dryer from Currys PC World was £20 cheaper than its “sale price” of £199 just two weeks before Black Friday.

Natalie Hitchins, Which? head of home products and services, said: “We have repeatedly shown that ‘deals’ touted by retailers on Black Friday are not as good as they seem.

“Time-limited sales can be a good opportunity to bag a bargain, but don’t fall for the pressure tactics around Black Friday.

“Our investigation indicates that this popular shopping event is all hype and there are few genuine discounts.”

However, Amazon disputed a claim Which? had made regarding Amazon Echo pricing and said that prices from third parties or deals which form part of a multiple product bundle will vary.

An Amazon spokesman said: “The claim from Which? with regard to Echo is false and we have made this clear in our response to them.

“Amazon.co.uk customers were not able to buy the Echo (2nd Gen) device cheaper before Black Friday 2018.”

Amazon also told Which?: “Our Black Friday sale is about thousands of deals on a huge selection of products from every category across the site, at a time of year when we know saving money is important to our customers.”

Currys PC World told the consumer group: “Our customers tell us that they appreciate the increased choice during Black Friday where we have the most deals on at once.

“When we launched our Black Friday event last year, 40% of those products were the lowest price they had ever been.”

John Lewis said: “In addition to the variety of offers we have in-store and online during the Black Friday period, our commitment to being Never Knowingly Undersold means that we continuously monitor and match the prices of our high street competitors throughout the year.

“As such, we offer our customers the best value on the high street all year round, including during the Black Friday period.”

Here are Black Friday tips from Which?:

1. Don’t impulse buy – Work out what you need or want to buy and how much you’re prepared to spend before you start shopping in the sales.

2. Don’t panic – Don’t worry about missing out on a good offer as Which? research has revealed that you could be better off waiting until after Black Friday anyway.

3. Find out about offers in advance – Sign up to your favourite retailers’ newsletters for inside tips, or check their social media pages ahead of the sales for any clues or hints to what will be on offer.

4. Look at the price on previous days, using websites such as PriceRunner, to make sure you really are getting a good deal.

5. Don’t always trust reviews you find online – a recent Which? investigation found shoppers risk being misled by fake online product reviews.

Vicky Shaw is PA Personal Finance Correspondent.