Hi all, unfortunately I need to join you.
Potty training has not gone well with dd2 at all (in retrospect dd1 was a dream) Started in November at 2.8 (3rd try) She has been dry at night since just after she was 2 
She sort of got wees although lots of accidents, didn't get poos or didn't want to do them on the toilet.
We started a reward chart for performing on potty/toilet & halped a little with wees not with poos.
So we were at home together a week & everytime I saw her wanting to poo I took her to the toilet. Nothing & I mean nothing for several days. She had literally just held on to it & severly constipated herself through sheer determination! We ended up at emergency docs on sunday morning as she was so so unwell. Not eating or drinking. Prescribed movicol, suppositories & anaesthetic cream. Back at the docs on wednesday & we were sent straight to hospital. They gave her picolax & said it would work in a few hours - nothing - I had to givea second dose of picolax & then 8 hrs later we had a result - rivers of poo! (sorry tmi)
She is now on movicol permanently, the consultant told me not to put her back in her nappies so for 2 months she has basically been pooing in her knickers. In addition as she got scared about pooing she is doing a little at a time - lots of clearing up. Her wees have got slowly better - she only has a wee accident now if she needs a poo too iyswim
On Monday morning she took herself to the loo & did a poo by herself, I cannot tell you how proud I am. She's also had a clean morning at nursery today so I really feel like she has turned a corner.
Sorry for the essay but I did think my experience might be useful for those in a similar situation.
RedHotPokers - sounds like he is just not ready. I would wait, try lots of stories about potty training, talking to him about how you & dd use the toilet etc. He may yet surprise you