bondgirl, my DS was very similar to yours and was a bit of a nightmare to put to bed aged 2. It does stop eventually, although i can't quite remember when he improved (he is 8 now). I don't think it's attention seeking as much as just really wanting you there when he's in bed (iirc).
Maybe you could strike a deal with him along the lines of, "bath, teeth, bedtime story, then I'll sit in the chair in your room until you fall asleep, but you must lie still with your eyes closed." Try not to engage with him beyond a short answer to any question, or a silent trip to the toilet if he asks. Keep everything really low key.
Once he's cracked that routine, you could say you will sit at his door til he falls asleep, then move onto the top of the stairs. Once you've managed that, you can say, 'just popping downstairs to get a drink', but take you time coming back, making the gap gradually wider, so he gets used to you not being there.
This is the kind of thing I tried - although the mistake I made was to try to rush the process, which can then set you back as they get all insecure again, and worried that you're not there. If you can muster a huge amount of patience, you will do it. It is really, really hard, but you have to surrender yourself a bit to the slowness of it all, and have a really good book on hand to while away the time.
My DS still 'summons' me a few nights a week because he can't get to sleep, and just needs a little stroke or cuddle to settle himself down. He's always been a bit of night owl, and finds it difficult to switch off and fall asleep. But the upside is he will sleep in the next day, so no early starts in the hols and so on.
Good luck, and try not to envy those with easy sleepers (my nephews just love their bed and I was always amazed at how quickly you could put them to bed compared to mine).
hth