Thanks again for the replies. Here is an update. Sorry it is so long, I am hoping it might help someone else.

SUCCESS!!!!!!! My little darling is going to sleep on his own in his cot for most of his sleeps. He still seems to want to feed-to-sleep at the middle of the night feeds, but for all his naps and for bedtime, I can go through our little sleep routine, put him in his cot, he might make a few sweet little noises to himself and then he?s out.

God I love him. I am so darn happy I could cry.

I ended up following pretty much the method Belle suggested above.

I had a sleep nurse visit me, from Hope Cottage in Ashfield. She actually took the time to get to know my baby, tried to settle him herself, and after assessing his temperament gave me a plan.

One of the best bits of this was that she validated my instinct that this was a very volatile bub who needs his mum. and leaving him to cry for extended periods was not going to work.

We go through sleep routine (wrap, womb-music, lights, music-box) put him in cot and left him for at least one minute. If he was quiet, leave him in cot. If he got upset, pick up him, rock / cuddle till calm, but not for more than 5 minutes. Put him back in cot for at least one minute. Repeat. I could use my own definition of ?upset?.
Her suggestion for if it took longer than 5 mins to calm him was to put him back down in cot for another minute even if crying ? but fortunately it rarely took longer than 5 minutes, and when it did, I was convinced he was too upset for the plan to work and just resorted to rocking him to sleep at that point.

After trying this together, she said normally she would say, don?t give up. But she listened to his cry and said, this baby is not ever going to cry himself to sleep or self-settle while crying, he is too upset, and once he gets worked up he doesn't calm easily. So, if he was not settled within 20-30 minutes, give up and rock/feed to sleep.

So, this plan did call for some crying. A whole minute at a time. I think this still qualifies as gentle parenting, but that is for you to judge for yourself. my assessment of my baby was that I had no choice other than to do this or give up, because initially he would go into crying mode pretty much instantly he was left in the cot and did not respond to patting, singing, etc. I felt that at 4 and a half months, it was not good that he regarded being in his cot for barely a minute, even with me by his side stroking his forehead and talking to him, as a class-one emergency. Consequently, for the first day or two of this, there was some crying. But over just a few days, the crying rapidly progressed from being ?distressed OMG the world is ending? and moved to ?this isn?t fair mum? and then got to ?idle whinge? and then, stopped. I even abandoned the plan completely at times when I thought he was overtired, or just working himself up. After the first few days, I have been able to go to his rescue and pick him up and cuddle him after a minute of grizzling, so no more crying at all. I hope I never have to do that again, because even a minute felt like an eternity.

(I can?t believe that first nurse who said I should let him cry for 15 minutes. My baby would have been so distraught at that point and I would have been too. Just cruel.)

At first it was just one nap, he fell asleep on his own first go. Then it was two naps in a row. Then three in a row. And it has now been 4 days where he hasn?t needed to be rocked at all. I started 10 days ago. He is happy as larry, and his naps are getting longer.

I think all the no-cry suggestions I did helped make this work (key words/phrases, routines, womb-music, etc). I think I had to give my baby opportunities to fall asleep in his cot. If I could have my time over again, I would put him in his cot at least once each sleep before resorting to the rock-to-sleep and perhaps I could have avoided this.

All the advice about listening to my own parenting instinct was spot on. I wouldn?t advocate this particular solution as being for everyone. I wouldn?t have gone to the extreme of even one minute of crying if I wasn't desperate (9kg baby? mother going back to work soon?I hated the thought of him being in childcare, totally unable to self settle, with carers who wouldn?t be able to rock a baby for 20-30 minutes... he would have cried till he passed out )

fingers crossed that this continues

thank you all I am so grateful