See also the individual 1GB memory for £11.99http://www.play.com/PC/PCs/4-/9216696/Kingston-KHX14400D3-1G-HyperX-1GB-1800MHz-PC3-14400-DDR3-Non-ECC-CL8-DIMM-Computer-Memory/Product.html
The 3GB kit appears to have the tall style heatsink see http://www.valueram.com/datasheets/KHX1800C9D3T1K3_3GX.pdf
which could be a problem for some systems.
* Total kit capacity: 3GB
* 1.7v - 1.95v voltage range for dual-channel applications for AMD based systems and Intel chipsets older than X58. 1.65v voltage for triple-channel Intel Core i7 9xx series applications
* 1.65v voltage for dual-channel Intel Core i5 7xx series and Core i7 8xx series applications
Kingston's KHX1800C9D3T1K3/3GX is a kit of three 128M x 64-bit 1GB (1024MB) DDR3-1800MHz CL9 SDRAM (Synchronous DRAM) memory modules, based on eight 128M x 8-bit DDR3 FBGA components per module. Each
module kit supports Intel XMP (Extreme Memory Profiles).. Each module kit has been tested to run at DDR3-1800MHz at a low latency timing of 9-9-9-27 at 1.65V. The SPDs are programmed to JEDEC standard latency DDR3-1333MHz timing of 9-9-9 at 1.5V. Each 240-pin DIMM uses gold contact fingers and requires +1.5V.