It’s a big distinction between US and U.K. legal systems. Without going into it in too much detail in U.K. attorneys fall into two categories, solicitors and barristers. Solicitors are legally qualified, licensed and authorised to give legal advice and representation to the public. We are also officers of the court, but we are not called to the bar as a barrister is and so do not usually * have rights of audience to represent and appear for parties in Higher Courts - for criminal law that’s a Crown Court. The accused will have been given access to a solicitor on arrest. That solicitor will have advised him at interview stage and will continue to represent and advise the accused to trial. The solicitor has now “briefed” a barrister to represent accused in OB which is a Crown Court. The Barrister (who is a senior barrister (known as leading counsel) as he is a QC having taken Silk) is likely now to represent him to and appear in his behalf at trial “instructed” by the sol.
*this will depend on whether you have become licensed as a solicitor-advocate, in which case yiu would also have higher rights of audience.
EDITED FOR MORE DETAIL