UPDATE - Thanks all for your help. Indeed I did look at all the links but as previous posters indicated it was either for Live Data or historical data only as recent as August 2021.
I emailed the local canton, who gave me me the details for the Cantonal Police and they have returned my email stating that "s’est produite une surcharge de trafic dans le tunnel de Glion et donc sur une bonne partie de l’autoroute A9"
They were happy for me to forward this to my insurer. I've now done that and I'll let you all know if they pay up (once I have argued over them applying the excess for four persons when I am only claiming for three - but that's another story).
As said, good luck and no harm in trying. But 's'est produite une surcharge' just means that heavy traffic happened- but not that this was exceptional or due to an accident.
UPDATE - Hello all - some of you might be (most of you won't) be interested to know that my insurance company has coughed up less the three excesses and the money landed in my bank account!
Great. So much for the nay-sayers on this thread.
Great- but you were lucky.
You know his policy conditions? Doubt any insurance did him a favour out of their goodwill...