Thanks for those. All of those things USED to work. If I go on a drive that takes at least an hour and doesn't involve stopping at traffic lights (he cries) he does still nap. But otherwise he's a big fella so the sling is not comfortable anymore and the bouncy chair has lost its magic too. I'd really like to train him to sleep in his cot so I can something else while he sleeps, rather than driving, walking and pushing his pram.
Ooh, well that's encouraging. The bed thing sounds interesting, but I was, perhaps naively trying to make his cot "the sleep place". He would, until recently, sleep anywhere. Beanbags were a favourite. But just as he hit the 3 month mark, the world suddenly got exciting for him and now, BF seems to be the only thing that makes him nod off. He'll sleep on my lap but that's not ideal obviously.