That made him the oldest player to appear in a Heineken Cup final, overtaking Perpignan's replacement hooker Marc dal Maso, who was 36 yrs, 3 mths and 10 days old when he played against Toulouse in the 2003 final in Dublin.
Thorn also replaced Leicester Tigers prop Darren Garforth as the oldest Heineken Cup winner. Garforth was 36 yrs, 1 mth and 19 days old when the Tigers won the 2002 final.
But his records could be overtaken by two Toulon players - lock Simon Shaw and hooker Sebastien Bruno. Two-time Heineken Cup winner Shaw played in all six Pool matches to help steer Toulon into the knock-out stages.
If he makes the matchday 23 for Dublin he will be 39 yrs, 8 mths, 17 days old, while former French hooker Bruno will be 38 yrs, 8 mths and 23 days. Bruno has figured in four Pool matches and the quarter and semi-finals.
ASM Clermont Auvergne's Nathan Hines is another candidate for the 'golden oldies' club as he bids for a place in his second Heineken Cup Final. The former Scottish international will be 36 yrs, 5 mths and 19 days old on the day of the 18th final.