Sandtrooper,
It is nothing to do with whether you have a business or not. It is a concession where AIM shares are included in the definition of 'qualifying business assets' for taper relief purposes.
Thus if you hold the shares for 1 year, 50% of your gains are non-taxable and the remaining 50% are taxable in the normal way. So some are covered by your annual allowance and any remainder are taxed at your marginal rate, which may be 40% or even less.
Assuming that your annual allowance is used up on other shares, then the effective tax rate on ALL of your TEO gains would be 50%x40% = 20%.
If you hold your shares for 2 years before selling, then the taper relief is 75% of the gains being non-taxable. Leaving only 25% taxable at, say, 40%.
The effective tax rate on your TEO holding would then be 25%x40% = 10%.
;-)