Ms Tennant and her team, now at NPI after the insurer bought them out from Jupiter Tyndall last year, have just launched a new unit trust that concentrates on generating income - quite a departure in a market that is overwhelmingly geared to smaller companies offering capital growth. NPI's new fund aims to yield a conservative 4.5 per cent initially after management charges - the highest income of any ethical or ecology fund.
Lee Coates, of the Cheltenham-based Ethical Investors Group, says income funds will be welcomed by his clients, who are not the loony-fringe investors they are often portrayed as. "Having income funds available will allow us to do a lot more business."
According to Micropal, which monitors unit trust performance, there is little difference in performance between socially responsible unit and investment trusts and the market as a whole. In the year to 1 August, ethical and ecology trusts underperformed their sector averages by 0.5 per cent. Over five years, however, they outperformed by more than 1 per cent.
But Patrick Meehan of Holden Meehan says that, of 30 socially responsible unit trusts, only two - from Friends Provident and Henderson Touche Remnant, which launched its first "green" fund in February - offer a "reasonable" yield - 3.6 per cent and 2.8 per cent respectively.
Funds also have to decide whether they are committed primarily to ethical principles or to environmental issues. Where Friends Provident's pounds 55m income fund takes a conservative approach to ethical criteria, NPI's income fund will venture where few ethical funds have gone successfully before - into large companies that may be less than ethically pure but are making strides on the environment.
Where NPI's Global Care ecology fund had some of the strictest ethical rules, and would not invest in BT, for example, because the company sells communications equipment to the military, in NPI's income fund BT's strong record in environmental accounting overrides any ethical drawback.
Jupiter Tyndall, whose Ecology Fund invests in companies that are "environmentally proactive", will take a less rigorous approach to firms' environmental records with the ethical income fund it intends to launch this autumn.
Fund manager Simon Baker says the fund, which is still in the planning stage and does not yet have approval from the Securities and Investments Board, will aim for a high yield of 7 per cent, with between 25 and 50 per cent of the portfolio invested in convertible bonds.
Like NPI's income fund, Jupiter's new fund will invest in BT, but not because of the company's environmental record. For Jupiter, the fact that less than 1 per cent of BT's turnover is military-related allows it to pass its ethical screens.
These new kids on the block have forced Friends Provident to take another look at its income fund. Like NPI, which will deduct its 1.5 per cent management fee from the income fund's share capital rather than from its income - allowing it to pay higher yields - Friends Provident is moving to take part of its 1.125 per cent management charge from capital, following a change in unit trust regulations last year.
But Stuart Dyer, director of marketing and sales at Friends Provident, says that he does not expect the yield, currently 3.5 per cent before management fees, to increase above 4 per cent after the change in September or October.