Thanks again for the advice. I bought some flexible silicon sealant. I cleaned the area on top of the sunroof and as much as I could reach below. Then I fed as much sealant as I could in to the area where the leak was coming from on each side of the sunroof. I also cleaned the drainage channels on the top and sprayed some ptfe lubricant in which I hope will help the water run away more effectively.
Once the sealant had dried I tested it again with water. And partial success. The drivers side is 'so far' dry and no leaks

. The passenger side though will need more work since the water still poured out from around the area I thought I had sealed.
I also bound the drainage hose with wire so it would not slide off again.
Judging by the effect on the drivers side it does appear that this approach will fix the problem. I'll persevere and have another go at the passenger side - I am hopeful I will sort it out.
Another quick question on lifting the carpet in the footwells. There is a plastic cover that sits over the door sill and the carpet. There doesnt seem to be an obvious way of removing it and I dont want to stress it and break it. How do I take this off?
Thanks
PTE