I can confirm that the Star Wars Black Series Stormtrooper with FX blast pieces has dropped to £14.99 at The Entertainer.
The figure has been sat at £24.99 for some time and is not shifting, but I suspect at this lower price point it will move quite quickly. It is also available online for the same price.
The figure is also being sold in Matalan stores. Matalan and The Entertainer have partnered up to put concession toys into Matalan in a section called "The Toy Shop", these are supplied by The Entertainer and are priced similarly. The Trooper in Matalan was priced at £12.49 a week or so ago, but that seemed to be an error. It is now at £24.99 but expect a cut soon in line with The Entertainer.
The Matalan deal of course does mean you can shop some of The Entertainer stock on a Sunday when the Entertainer stores are closed.