The thresholds determining company size for accounting purposes have changed in the UK as of 1 January 2016.
UK companies will be required to have an audit if it meets any two of the following three limits:
-Turnover over GBP 10.2 Million
-Total assets on the Balance Sheet more than GBP 5.1 Million
-Number of employees more than 50.
Of course, companies will also have to have an audit if the mother company requires it.