The following information is available:

(a) On 9 May 2013, Steven bought 2,000 ordinary shares in Vexacon plc for £8,000. On 28 November 2017, he bought a further 500 of the shares for £2,500.

(b) In March 2023, Danshore plc offered the shareholders of Vexacon plc two shares in Danshore plus £2 in cash for every Vexacon share. This offer was accepted on 21 March 2023, when the market value of shares in Danshore plc was £4 per share.

Compute Steven's chargeable gain or allowable loss.