The headcount tells its own story. In June, Grant Thornton employed 1,500 people in Ireland. By the end of December, the number had swelled to 1,800. In between, the firm unwrapped plans to boost its size by a further 1,000 staff over the next three years. For Michael McAteer, the firm’s managing partner, the October expansion announcement was both a statement of future intent and an acknowledgement of the buoyancy of the market right now. Indeed, McAteer acknowledges that the biggest issue for the firm right now is not sourcing clients but finding the right staff to service them. “The…