You know what I reckon might have happened the previous owner may have dropped one of the bolts that hold the plastic covers and it has disappeared inside the radiator shroud and was not able to see it so presumed lost and he replaced it with a new one and it has taken this long to fall out ..... just saying there's a lot of nooks and crannies in there that would love to hold and hide a bolt .... dont ask me how I know .
............... Ok I 'll tell you! don't twist my arm, I removed my entire rad shroud and started to remove the radiator looking for a bolt once only to find it sitting in the cover around the fan