The trust, managed by Matthew Dobbs, has delivered a return of 111 per cent in the past five years and is on a premium of 2.81 per cent, having been trading on a premium since halfway through 2011, according to data from Morningstar.
The share issue will be in three tranches, available separately to institutional investors, existing shareholders and retail investors.
The trust said it would consider raising the share issue total to £150m if it received enough demand from investors.