Shell has run three versions of the Shell Make Money game in the UK.
THE 1966 VERSION
The first, in 1966 (above), offering cash prizes of up to £100, was created and supplied by Ralph Glendinning of Glendinning Associates, an American marketing consultancy. The game was a huge success but there were grave doubts about the legality. Shell was concerned about the possibility of being prosecuted in the UK for conducting an illegal lottery. Shell was also rightly concerned about the security of the half-note currency.
More information further down this page.
THE 1984 VERSION (THE MAIN SUBJECT OF THIS ARTICLE)
The second version was launched in 1984 (envelope above) offering cash prizes of up to £10,000. It was created and supplied by Don Marketing, a UK promotional games company founded by John Donovan, his family, and Don Redhead, a Chartered Accountant/mathematician. Don Marketing supplied a QC’s opinion to Shell confirming legality. The promotion, known internally as Operation Leo, was a huge success.
and its sister non-profit websites royaldutchshellplc.com, royaldutchshellgroup.com, shellenergy.website, shellnazihistory.com, royaldutchshell.website, johndonovan.website, shellnews.net
are owned by John Donovan.
There is also a Wikipedia feature.