A change in country of origin has sparked a dramatic increase in the price of red seedless grapes this week. The average price of a 1kg punnet has risen by an average of 11.8% with Tesco sporting the most significant increase of the six other retailers on our list. Its price has risen by 20.1% from £2.49 to £2.99 this week.

Prices also rose by 20% at Morrisons and Asda, while Somerfield's price increased from £2.99 to £3.49.

Increases were not recorded at Sainsbury's and Waitrose, which were already carrying the higher prices.

As the all important Christmas period draws ever nearer, this week's report shows the top six starting to up their promotional offers. Asda led the way in volume of offers. This week's mystery shopper spotted 17 different types of offers on items on our list.

However, these were not quite enough to restore the retailer to the position of cheapest supermarket.

That title was once again reserved for Tesco whose basket rang in at £62.18. The 69p price difference between the two retailers was largely driven by the price of Old El Paso fajita dinner kits, which are currently on offer at Tesco for £1.33. Both retailers were matching each other for price on 29 of the 33 items on our list.

Prices of Mr Kipling's apple pies have also risen by an average of 10p across the board this week after a promotion ended.

At £64.43 Sainsbury's was the week's third cheapest retailer, and 29p cheaper than Morrisons, which slipped back down the pricing tables to fourth place.

Morrisons was marginally more expensive than its nearest rival for a range of fresh produce items including Cheddar, pasta, bacon, and chicken according to this week's report.

Meanwhile, despite continued claims of price cutting, Somerfield produced the most expensive basket of the six.

It was also carrying the highest prices for all of the kitchen and bathroom goods on our list.