Thanks Harrock n roll for helping with constructive remarks.
Actually it seems E.P. Jacobs started to work with Herge on January 1st, 1944
and left him in 1947, after less 4 years' collaboration for Tintin (about 3 years before the Studios were founded)
Olav*, the dual pseudo for 'Herge & Jacobs', is mainly connected with Le Canyon Mysterieux, a story drawn by Paul Cuvelier (1923-1978).
Other details on http://en.wikipedia.org/wiki/Herg%C3%A9EDIT:
About "Le Mystere de la Grande Pyramide " (Blake et Mortimer, p.42), the shop front actually reads Herge - & Ca
According to Assouline's biography, Herge was left by E.P. Jacobs essentially because of his arrogance, that consisted mainly in refusing systematically EPJ's name to feature on the Tintin albums, besides his own.
This attitude towards him -not to mention the conversations they might have had about Tintin- likely made E.P.Jacobs realize there was something very personal between Herge and Tintin.
Like Herge, he was a very meticulous draughtsman; he might thus also have noticed the many inconsistencies inserted and tolerated in Herge's albums (such as duplications, impossible speeds for vehicles or growth, etc), not to mention the hundreds of spelling mistakes found in the original versions.
In that context, the speech bubble just above Herge's name "Il a l'air bien bizarre!... Mais que fait-il donc?... ", namely "How strange he looks!... What the h... is he doing?..." might have been more than just a small compliment...!
[Moderator action: combined 2 consecutive posts.]