There are a number of different ways to find a suitable Psychologist. The Court may recommend one or you could ask your solicitor or barrister if they can recommend one they have worked with in the past (and respect). You can also look for one on the British Psychological Society website where you can see details of their qualifications and areas of expertise.
In 2012 an investigation found that 20% of Experts in cases lacked any qualifications and a further 20% lacked the necessary experience to act as an Expert witness in that specific area. You can check whether a Psychologist is, in fact, a practising Psychologist via the Health and Professions Council (HCPC) statutory register:
Recent criticism of Expert Witness Psychologists largely revolved around Chartered Psychologists who were academics, or senior consultants, and did not carry a current case load working with clients on a regular day-to-day basis.
Past complaints to the British Psychological Society may be upheld against a Chartered Psychologist, yet that Psychologist would still be able to practice if there was no HCPC complaint – another reason to check the HCPC Register!
As with any professional, some are more suitable than others and have a better reputation. If you are using a solicitor or barrister, their recommendation is important, since they will have seen the quality of reports previously provided, how the Psychologist stands up to cross-examination, whether their findings tend to be ambiguous and open to challenge or whether their reports are precise and well founded.
The main association for Psychologists is the British Psychological Society. Check specialisms, qualifications, and locations on the BPS website.