Thanks for your help Jiggy.
Currently, I have a good messenger bag, it’s a crumpler, really good quality. I really do like it, but the problem is that now I am taking really crowded tube and I found the messenger bag not really suitable for this, it’s not easy to pass through people with the bag on a side.
For instance also, in the escalator, it’s more convinient to have a backpack than a messenger bag for the same reason as above.
By the way Jiggy, the bag you are talking about seems really nice, I can believe you for hard conditions testing :D .
Julien.