I began by purchasing Autobrite's "Berry Blast Endurance Trim & Tyre Gel". (This can be purchased here). This stuff works by leaving a very fine, clear film over the area applied.
This is how I carried out the restore:!
1) First thing to do is make sure the trim is clean and free of bugs etc, this product really does work better if the area it's going on is very clean - ideally give the whole car a rinse before hand!
2) Apply a small drop of the Berry Gel (smells amazing by the way) to a foam applicator pad such as as this.
3) Apply the gel to the required areas but don't put too much on - you'll be amazed at how much area you can cover with a small drop.
4) Leave to dry and be happy with the results.
5) Optional - apply to wall of tyre as a tyre dressing, you should only need about 4 drops max of the gel.
And here's a couple of photos after I'd done the rest of the car and left it about an hour in the sun to fully dry.