Diana Paulette Wallis, FCIL (born 28 June 1954[1] in Hitchin, Hertfordshire) is a British former Liberal Democrat Member of the European Parliament (MEP) for Yorkshire and the Humber.

[18] As Rapporteur to the Committee of Inquiry into the Equitable Life affair, she is author of a report which was approved by a large majority in the Parliament and which made a number of recommendations prior to the economic and financial crisis of 2008, including the "further strengthening of prudential supervisory and regulatory standards throughout the Union", in order to avoid such a situation recurring in the future.

Throughout her time as an MEP, Wallis has authored 28 full reports excluding purely technical ones, and 16 opinions, asked 40 written and oral questions of the Commission and Council (during Parliament's 2004–2009 term).

[21] On 30 November 2011 Wallis announced[22] her intention to stand for the position of President of the European Parliament as an independent candidate on the basis of nomination by 40 MEPs from different political groups.

Martin Schulz was elected on 17 January 2012, as anticipated, and pursuant to the agreement between certain political groups, with Wallis obtaining 141 votes.

Wallis had been due to be succeeded by her husband Stewart Arnold who was also employed by her as a Parliamentary Assistant,[24] who had been second on the list of Liberal Democrat candidates for the seat in the 2009 election, but he declined the appointment and eventually went on to found the Yorkshire Party with Richard Carter.

In March 2006, she hosted an IRI-Europe conference in Brussels to discuss different approaches across Europe towards the issue of direct democracy and in particular the campaign for introducing a citizens' initiative at the European level.

Before and after the entry into force of the Treaty of Lisbon, she played an active role in shaping and implementing the European Citizen's Initiative.

[28] In this framework she met Commission President Jose-Manuel Barroso in a bid to increase gender equality within the College of Commissioners.

Wallis is a Member of the European Emergency Number Association (EENA) Advisory Board She completed the London Marathon on 26 April 2009 in a time of 5 hours 22 minutes, running in aid of the World Endometriosis Research Foundation.