10% of difference = £5.83 | 110% price promise makes this £25.90 @ PCWorld.
As PCWorld's "Web exclusive" price is £58.99, then if you want to reserve the item before picking it up, you will only get a match on the "Web exclusive" price quoted to you online. This would make it £29.00. (Although with this method you could also go through QuidCo for another 2.5% off making it £28.28.) There seems to be loads of stock, so there's probably no need to reserve online before picking up anyway.