Late last year, Procter & Gamble and activist investor Trian Fund Management — combatants in the most expensive and contentious proxy battle in US history — took their fight to the “snake pit,” a rarely used venue where close proxy votes are resolved.

For three weeks, 30 participants, including proxy solicitors and outside counsel for both P&G and Trian faced off across a table in a nondescript 13th-floor conference room in a business centre in downtown Wilmington, Delaware.