Interesting Comments on Simon Dixon Books
http://www.amazon.co.uk/review/RH8X6BJGJ3JJN/ref=cm_aya_cmt?ie=UTF8&ASIN=1907720375#wasThisHelpful

Reviews of Benedix, one of of Dixons previous companies
http://www.thestudentroom.co.uk/showthread.php?t=980864

Simon Dixon Companies House History
https://beta.companieshouse.gov.uk/officers/WLCQQ18wZCJItYxibbHAwdkccYc/appointments

The beta companies house website gives you access to latest company filings.
https://beta.companieshouse.gov.uk/company/08624882/filing-history

Looks like Max was planning his exit in July and cashed out then during the peak.

Termination of appointment of Wing Yi Grace Ma as a director on 14 August 2015
Termination of appointment of Jamie Scott as a director on 18 August 2015

No doubt the confirmation of Termination of Max will follow as Director's details changed for Mr Timothy Maxwell Keiser on 24 June 2015.

Max today: https://twitter.com/JopHartog/status/647808644478816257