By Charlie Conchie The City minister is set to meet top start-up groups to discuss softening its controversial investing rule changes, after a backlash from the industry and pressure from another government department. So-called angel investors launched a campaign against the Treasury on Wednesday over changes to the definition of ‘high net worth individuals’, which they say could potentially shut off millions of pounds of funding for smaller private companies. Under the tweaks set to come in next Wednesday, the financial threshold of ‘high net worth individual’ will be lifted from an annual i…