It’s a rare honour for any amateur player to play a reigning world champion. How many Irish players can claim this distinction? The number must be very small.
One player who can is J. J. Walsh. And here is the evidence: the scoresheet signed by Botvinnik himself:
Ireland played the USSR in the preliminary rounds of the Munich Olympiad 1958. Botvinnik had regained the world championship title earlier that year, winning his return match against Smyslov. [Click to play through the full game.]