The Class 450's were constructed from 2002 to 2006 by Siemens in Krefeld, Germany. These trains are my favourites and is my childhood train.
Class 450's nowadays wear the SWR livery which is quite bland. The older SWT livery as shown above is what I grew up with.
The Class 450 have gone through 3 types of interiors. The 1st one was the SWT interiors, which are my favourite. (See the Class 455 page on what they looked like.)
The 2nd one shown on this image here is the first version of the SWR interior while the 3rd one is a minor tweak to the seats for easier cleaning.