He is a former member of the UK Prime Minister's Business Advisory Group.
In June 2014 Dilley was awarded a knighthood by Her Majesty The Queen for services to consulting engineering.
That same month the Coalition Government announced Dilley would take over from Lord Chris Smith as chairman of the EA.
The appointment caused some controversy over a perceived conflict of interest regarding Arup's involvement in the fracking industry in the UK and the Environment Agency's role as its regulator.
In October 2015 Dilley became an ex-officio member of the board for the Department for Environment, Food and Rural Affairs (DEFRA). 
- Arup, former chairman, remains a trustee
- London First chairman of this business organisation
- board member Grosvenor Group later this year.
- honorary fellow of RIBA (Royal Institute of British Architects)
- member of the Governing Council of Imperial College, his alma mater.
- Dods People, 'Arrivals, moves and departures', Civil Service World, 26 October 2015, accessed 2 November 2015