While Capital Gain Taxes have been slashed in the recent budget to 10% and 20% (from the 18% and 28% that it used to be), CGT has remained unchanged for residential property gains. While the tax rate for gains is lower than the one for income, amounts tend to be much bigger and far appart, making it harder to use allowances and low rate bands.
This is where deferral comes in handy. The Enterprise Investment Scheme (EIS) provides one of the mechanisms that allows such a deferral. Most people misunderstand that the general EIS conditions for income tax relief are much more restrictive than the conditions for CGT deferral. In particular the requirement that one owns less than 30% of the company or that one is connected to the business only applies to the income tax relief component of the EIS, not the CGT deferral. Same thing for the requirement that the investment be held 3 years or more: if you sell earlier the deferral just ends then (see HMRC note).