Hi All
With regard to the question; whether or not a logbook has to be carried on board, I found the following:
FCL.045 Obligation to carry and present documents
(a) A valid licence and a valid medical certificate shall always be carried by the pilot when exercising the privileges of the licence.
(b) The pilot shall also carry a personal identification document containing his/her photo.
(c) A pilot or a student pilot shall without undue delay present his/her flight time record for inspection upon request by an authorised representative of a competent authority.
(d) A student pilot shall carry on all solo cross-country flights evidence of the authorisation required by FCL.020(a).
In the view of an OPS-inspector, without undue delay might mean before he leaves/releases the aircraft!
Cheers,
g5tom