The former England and British and Irish Lions prop became the first ever front-row forward to make 100 international appearances.
He was also the first Englishman and overall third (after Philippe Sella and David Campese) to achieve this feat.
Despite being regarded as the third-choice England prop behind Phil Vickery and Trevor Woodman in the 2003 World Cup, Leonard made appearances in all seven matches of the tournament, including the semi-final against France during which he overtook Sella as the world's most-capped player at that point.
He appeared in his second World Cup Final as an extra-time substitute and played a key role in reducing the scrummage penalty count which then coach Clive Woodward would later write in his autobiography that Leonard's introduction was the key substitution which helped England win the match.
Having been awarded an MBE for services to rugby earlier, his award was upgraded to an OBE after the tournament.
At the evening, which is in aid of the Wooden Spoon charity, there is also a raffle auction included in the £49 per person price. Proceedings start from 7.30pm. For more information or to book tickets please call Sybil Buijnsters on 01905 454183.