Any idea where I can get a rear light seal on its own?

[Coco1547]

HI guys, Let me start of by saying this is my first post and it's a pleasure to meet you all. 

I was just hoping somebody could provide me with some idea where to look for a specific seal, the seal that I'm looking for is the near side back light seal on a MK7 (59 plate) Fiesta. I changed a bulb in the misses Fiesta the other week and noticed the seal was looking a little shoddy. Until we replaced the bulb there was no problems but since changing it she now has a leak in her boot coming from the light, so its clear I must of disturbed what was left of the seal when changing it. 

The rest of the light assembly is great condition so don't really want to spend 50 quid on a whole light assembly when its only a 50 pence part that's gone kaput, unfortunately due to bad weather we haven't been able to apply a solid layer of sealant either as every time I put it on ten minutes later it tips it down. 

I have scoured the internet ruthlessly but can't seem to find just a Rear light rubber seal and was wondering if anyone here could point me in the right direction. 

Thanks a lot for absolutely any help anyone could provide it would be greatly appreciated and I look forward to reading your responses.

 

[GingerFlame]

Ford, or a complete light from a scrapyard 

 

Or, improvise :)