Until 31 December 2013 the Brixton Pound had a bonus of 10% for those who exchanged their pounds sterling into the local currency, meaning that £100 of national currency would buy B£110.
Once in circulation the exchange rate between Brixton Pound and pound sterling remains at one-to-one: the bonus functioned as an encouragement to convert to and use the local currency.
It also had a malus of 10% for those businesses who exchanged their Brixton Pounds into pound sterling. The malus functioned as a disincentive to convert and an incentive to find local suppliers to spend the Brixton Pounds with.