Here are a series pics of the drives side procedure
First I took off the seal 
Then undid the Stainless steel strip 
I then Pealed off the foam backing. On the passengers side I went great lengths to remove the old glue but decided to leave it on on the drivers side. 
I put one strip of sealant under the roof first. 
Then did two strips of sealant over the entire length. 
I screwed the stainless steal strip in place straight away coursing all of the sealant to squirt out. 
I removed the excess with my finger trying not to leave holes like the one in the photo. 
I made sure I had plenty of sealant covering both ends.
I left the car with the hood down in the sun to dry for a few hours before refitting the seal and putting the hood up.
I’m not sure this is the best way of doing it but its worked for me. I have a rather split old roof which I’m assuming not to be original as its a Tan roof on a red car with black interior. Even with the very wet weather we have had recently the car has stayed dry inside with out the need for a new roof.
Thought I had better give you an up date
After the dry spell, we have had a lot of very heavy rain and my car decided to leak again.
I discovered the course of the problem. When refitting the stainless steel strip I had put it as far to the outside of the car as possible to get a good seal on the window. This did indeed give a very good seal on the window so good in-fact the window got pushed out by the seal. This then meant the quoter light was also pushed out coursing all of the rain running off the join at the top of the windscreen to miss the top of the drain and ran down the window into the passengers and drivers foot-wells.
Now I realise there was a good reason for the stainless steel strip being positioned in the middle of its travel.