They are standard clips not Fir Tree!!
The one clip on the top by the lock pin must be a Fir Tree type and not a standard type. Fir Tree as in it looks like a Fir Tree!! A standard clip will hold for a while and then pop out.
This is what you need all of £2.20 each and only one for each door.
Ed.
http://cgi.ebay.co.uk/NEW-GENUINE-MG...item41554d7d1a