The Kingsbury Radiator Muffette (sometimes refered to as Grille Muff) is a rare factory accessory used to cover the radiator grill in cold weather conditions. It was most often seen on Alpine Rally cars but was also available on any MGA as a dealer option. There was a slightly smaller size (different part number) made for the MGA 1600-MK-II with the modified grille. The small pegs would attach to the grille slats with no drilling required and could be left in place. The central cover flap could be rolled back and secured with snaps in various positions to adjusr air flow. This one appeared an eBay in November 2007. For as long as the link lasts you can see it here:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140175529311