Proud cut gelding

Question
I recently came into possession of a 17 yr old gelding.
I noticed all of the neighbors mares, backing up against the fence toward him, and he is getting an erection.
I've spoken to my neighbors, and they say that he is "proud cut".
I've gone on the internet an researched the meaning, and there seems to be a lot of differing opinions on the subject. My question is, can anything be done at this point to rectify a botched castration, that was done 16 yrs ago??

Answer
Hi Tom,

I would say possibly a hormone regulator from your vet to control the hormones he still has, and possibly, if the vet who messed up the original castration is still in practice, I'd be suing!  

I really wouldn't say anything surgical at this point in time, unless he is VERY fit and healthy, and it is absolutely necessary.  To me, it sounds like he's still got 1)some testicular tissue and 2) some excess testosterone in his system.  It may be useful to get him tested to see if he is actually fertile/producing sperm, then you know to keep him away from in season mares.

Emma xx