Not really. Almost all Uber drivers in London used to be minicab drivers (or work for e.g. Addison Lee), and the pay, rates, customer-base etc. are similar.
It's natural - you still have to be licensed with tfl to drive uber; all minicab drivers were already licensed; uber is a better platform to drive for than a shitty call-in minicab company. So most of the drivers switched, and only people who have got licensed after uber showed up don't count as 'used to be minicab driver's.