Simons said: "I will be looking to build on the senior team at Truly. We have just appointed Adam Sunderland as managing director of Truly Middle East and Carl Walsh recently came on board as media director of Truly London. We also intend to recruit a managing director and planning director for Truly London in the medium-term."
The appointments are expected to be made within the next year. Current managing director Jeremy Aspinall is due to take on an as yet unspecified new role.
Truly London was known as Smarter Communications until a shake-up in October last year that recast Smarter as the umbrella company for a network of agencies, including Truly London and new launch Truly Middle East.
Simons was brought in at the same time as non-executive chairman of Truly London, which dubbed itself a "coalition of communications skills", including creative, media and other marketing specialisms.
Now in addition to being handed the reins at Truly London, he taken a stake in Smarter Communications Group for an undisclosed sum and been given the role of group chairman.
The founders and majority shareholders of Smarter are group chief executive Adam Shoefield and group chief strategy officer Graham Hawkey-Smith.
Shoefield said: "Paul has made a big contribution over the last six months since he joined us. We recognise the value he can add across the board in taking the business to the next level."
Simons' former venture was the marketing services group Cagney, which he founded in 2005 after leaving Ogilvy & Mather in 2002.
Cagney acquired around five agencies, including creative shop Walsh Trott Chick Smith and PR agency The Media Foundry; it floated on the Alternative Investment Market in 2006 trading initially above £8 per share.
He resigned as chief executive of Cagney in May 2008 when the group's share price was below £2. It is currently trading at 60p.
Smarter Communications includes Truly London, Truly Middle East, strategic marketing consultancy Truly Consulting, web design and e-commerce agency Leftfield and online marketing specialists Forty2.
Clients include The Isle of Man, AIG, Air South West, Nakeel, Fred Olsen Cruise Lines, Nuffield Health, and Jack Russell Clothing.