Hi
 There is no Zimmermans in this book. There are several Bakers one Charles E Baker  are you sure is initials where C H Baker?
This is a poss with first  name Charles
Born May21st 1889 entered service Jan 11th 1915, left March 1921-reason Depression in trade.
Job  on no.1 and 2 docks  grade - Tip cleaner rate of pay 3/10
 grade- Tipper rate of pay tonage date of removal Jan 22nd 1915
Tip Cleaner :porter rate of pay 76/-  date of removal feb -28th1921  amount 76/-
note under Tip cleaner porter -regraded depression in trade.
At bottom of page-Enlisted Sept 17th 1919
                              Resumed dutyJune 10th 1919 
I believe thoes dates are to do with enlisting in army althought in this case the dates do not make sense?
I have no idea if this is who you are looking for due to the middle initial being different.
Regarding where do you get info from I don't know I was luck to be given this book / Register Its a shipping Book No. 2. I look people up if there are there then thats great.
 At least it shows everyone what sort of info is in the book
cheers cardiff 
 