London stock exchange SETS opening auction

Just wondering, if all orders in the LSE SETS opening auction are executed at an uncrossing price, and the uncrossing price is the official market opening price, how can anyone entering orders in the opening auction actually benefit?

And by benefit i mean execute at a bid (if going long) lower than the market open or execute at an ask (if going short) higher than the market open.

If auction uncrossing price = official market open price, then what price advantage is there for traders with direct market access for participating in the opening auction?