Group dining near Maidenhead
We've got a conference next week near Maidenhead and need somewhere for a group of 10. Gastropub would be ideal. At the same event last year we went to the Hind's Head which was lovely, but the bill somewhat hefty (probably driven by the wine list prices).
Your problem is that the area is extremely wealthy. You will be up for a large bill even at somewhere pretty average, so the places that are good tend to make the most of it on the markups.
As Zuriga said, the Royal Oak is the benchmark in the area. They are a bit cheaper than Hinds Head (and I think the food is better). The next layer down is good country pub with all that entails.