They are treated as dividend income! There are separate rules for income from salaries (and pensions), dividends and interest, as well as capital gains which are treated as income in some ways.
One point, I think you'll find that Edinburgh has ceased to exist, most of it has been bought by Aberdeen, which is beset with problems at the moment. Several of the Edinburgh ITs have moved elsewhere, including the flagship Edinburgh IT which has gone to Fidelity. If you want a big, relatively low-risk IT the best bets are indeed probably Witan and F&C, also Alliance.