Capital Gains on LTI Shares

I have LTI shares with my employer which I opted to sell once the vesting period was complete, my employer has withheld tax on these at the relevant rate to my tax band but do I also have to complete capital gains return or is the tax covered with the employer withholding tax as its part of LTI that I have disposed of at the earliest possible time so no capital gain made from time that shares were released from vesting to being sold?

Hi ,
 

Please refer to guidance at : Tax and Employee Share Schemes   . Thank you .