THE PROBLEM commercial law firms face is that they continue to be judged on the crudest of financial metrics - profit per partner - while their practice mix can lead to large variations in that figure.

Take MacRoberts. Having had its best financial year since 2009/10 in 2015/16, both its turnover and profits slumped in the subsequent year, with overall profitability falling to its lowest level since the firm converted to an LLP a decade ago.

The reason? A lucrative role on the Scottish leg of what came to be known as the Rangers big tax case came to an end in 2015/16, meaning the £2 million in fees it booked in that year were not to be repeated.

The problem with big-ticket litigation is that while it can earn a firm a high profile - and in this case it didn’t because MacRoberts’ role was confidential - it can also lead to wild oscillations in financial performance.

Unlike transactional practices, which tend to bill clients on an ongoing basis, litigators charge for their work when the matter they are advising on concludes.

When that matter is worth £2m it can make a major impact on a firm of MacRoberts’ size - and people only tend to notice it when it is gone rather than when it is earned.

But with future recruits still using profit as a means of differentiating between future employers, and MacRoberts relying on expansion in Dundee and Edinburgh to boost its financials in the near term, the firm will be hoping the 28 per cent bottom-line growth it has recorded in the year so far translates into a full-year bump of the same level.