Yep, but if you follow that through the attempted bit would surely automatically come into effect i.e. you couldn't have attempted GBH as by the very nature of attempting to cause GBH you are showing the intent so you either drop the attempted or the intent part? Also, in this case surely he actually caused GBH rather than just attempting to do so or did none of the injured meet the threshold for "serious injury"?
Think you are mistaken in your logic and getting to hung up on words and confusing attempt and intent.
Take muder - as the offence - you would presumably accept it is possible to attempt to murder someone. Murder requires "malice aforethought" ie intent
for example if I get a gun with the intention of killing you. I fire the gun at you, but as I am a crap marksman I miss you with the shot. That is still attempted murder as I with malice aforethought ( ie intent) attempted to kill you
Same with GBH with intent - eg I get a car and drive it at you intending to cause you really serious harm, but whether by luck or lack of driving ability I fail to cause you serious harm and you suffer no or minor injuries, I would still be guilty of Attempted GBH with intent
I attempted to cause you really serious injury (GBH) and the intent is proved by the fact I got a motor vehicle to do it with ( ie the intent)
If I punch you in a pub after you insult me and cause really serious harm, that is GBH and not GBH with intent as I had a momentary loss of control and did not form the necessary intent to cause you really serious harm. If however after you insult me, I pick up a bottle, smash it and hit you with it, then that would be GBH with intent, or if fortunately you were able to avoid my use of the bottle, it would be an attempted GBH with intent