1. Alex Pusco, Activtrades (17=)
A former personal broker for high-net-worth individuals, Swiss-born entrepreneur Alex Pusco used the internet to expand his client base, establishing one of the first European online trading platforms in 2001. He moved the sales hub of ActivTrades to the City in 2005 before diversifying into his current mainstays of forex and spread betting. ActivTrades also offers services to institutions needing support for their portfolio managers and to independent brokers, as well as technology allowing punters to trade via their smartphones. Pusco is reportedly looking at setting up a South American operation. In 2013 ActivTrades made a £9.3m profit on £22m sales.
2. Lance Uggla, Markit (21)
Lance Uggla provides banks with vital trading data
Canadian bond trader Lance Uggla first came to London to study at the LSE in 1986, but it wasn't until 2001 that he started up financial data provider Markit Group in a barn near his then home in leafy St Albans, Hertfordshire. About to turn 40, he was in the mood to go it alone and reckoned he had spotted a gap in the market for a service that provided banks with vital data about the volume and prices of their trades with each other. It worked and he now employs some 800 staff in his London HQ alone, and has 22 offices around the world. Markit floated on Wall Street in June valued at around $4.3bn, but Uggla remains committed to the UK capital. His fashion-student daughter, Riley, has featured on reality TV show Made in Chelsea.
3. Ayman Asfari, Petrofac (34=)
Ayman Asfari turned a modest US business into a world-class outfit
Ayman Asfari runs oil services group Petrofac, a FTSE 100 business that manages oil rigs from Aberdeen, via the UAE, to India, as well as designing drilling and refinery equipment. The son of a diplomat, Syrian-born Asfari made his first fortune building roads for oil exploration outfits in Oman. By the age of 28 he had getting on for $3m in his pocket and decided to go it alone, buying into Petrofac - then a small US outfit devoid of global ambitions - with his partner, Maroun Semaan. Now based in London, he led the £742m flotation of Petrofac in 2005. The business is worth £3.5bn, with net profits of $650m on revenues of $6.3bn in 2013.
4. Subaskaran Allirajah, Lycatel/Lycamobile (38=)
London-based Sri Lankan refugee Subaskaran Allirajah founded Lycatel in 2004, selling prepaid cards for discount phone calls. In 2006 he launched mobile virtual network operator Lycamobile, leasing capacity from the likes of O2 and Orange to provide customers with no-roaming-charge mobile SIM cards for international calls. Despite hitting the headlines for its controversial tax arrangements (as well as Allirajah's donations totalling £420,000 to the Conservative party), Lycatel is now the world's largest cheap international calls network, operating in 16 countries with more than six million users. It made a £6.5m profit on £470.9m of sales in 2012-13.
5. Hamid Guedroudj, Petroleum Experts (53=)
In 1990 Algerian-born Hamid Guedroudj started Petroleum Experts, an award-winning Edinburgh operation providing high-tech modelling software to the oil industry. It has some 350 clients globally - including BP, Shell and Chevron - and the innovative digital-mapping tools developed by Guedroudj have been used to boost production efficiency in more than 200 oil fields. And yet when he started out, despite 13 years as an oil consultant, no one would back him and he had to build the business from scratch with no outside funding. Consequently, he retains full control of Petroleum Experts, which grew by no less than 240% in the five years to 2012. In 2013 the business made a record £29m profit on £38m sales, up 50% on the previous year.
6. Kuljinder Bahia, Southall Travel (61)
Southall Travel is a fast-growing operation originally based in the eponymous west London suburb, run by Kuljinder Bahia. Born in the Punjab, Bahia took over the firm in 1997 aged only 24. He made his name offering flights and tours predominantly in India, but also in Nepal, Bhutan, Tibet, Sri Lanka and Dubai. More recently, Southall Travel has branched out into corporate and wholesale travel and in 2013 launched its own website, Travel Trolley. Now headquartered in Buckinghamshire, in 2012-13 Southall Travel's parent company, Onkar International, made £14.8m profit on £283.3m of sales.