https://www.slab.org.uk/faqs/special-reviews/
In exceptional circumstances the committee may instruct a special review be carried out at any time. These will be undertaken at our expense at your firm’s premises and will follow the procedure of an extended or final review.
If your firm passes a special review it will not be subject to another routine review until the next cycle but may, in exceptional circumstances, be the subject of another special review at any time.
If a firm or a solicitor fails a special review it will be subject to either an extended review or a final review depending on the stage that has been reached in the process; and may, pending final review, be subject to further special review.