Philip Hammond’s long-serving Special Adviser Graham Hook has left government. Hook, a dependable and highly-experienced Whitehall veteran who has worked across four departments, served under Hammond since 2012 and will be a major loss to the Chancellor. Guido hears he left in May and has joined the Investment Association. This is the second major SpAd departure from the Treasury after Hayden Allan left in April. Does not bode well for Hammond ahead of the post-election reshuffle…