And yet the Suffolk WT page for Bonny Wood claims "lesser twayblade" in the species listing, as you noted originally. Surely the fact that this isn't highlighted, yet "The luckiest of visitors might even be able to spot a greater butterfly orchid", suggests a simple error in that case...wouldn't be the first time i've seen a common twayblade 'identified' as lesser... The BSBI record is more interesting -- i've pinged the county recorder, and the Bonny warden, and will report back here on any responses.
[Don't suppose anyone has easy access to the Suffolk Naturalist's Society 'A Flora of Suffolk'?]