A desire to retain talent has been cited as the driver behind an increase in partner promotions at the U.K.'s top law firms this year.

Most of the largest 20 firms have promoted more partners than they did in 2018 and several have managed all-time or 10-year highs.

Magic Circle firms Freshfields Bruckhaus Deringer, Clifford Chance and Linklaters each made up the most partners since the financial crisis, while Allen & Overy made up 70 percent more partners in 2019 than it did last year.

In 2018, the Magic Circle promoted significantly fewer lawyers to partner, making up a combined total of 88 partners. This year, that figure rose to 120, despite Slaughter and May promoting just one lawyer this year.

Out of the top 20 U.K. law firms, only five promoted fewer partners this year than last year. A robust market has allowed firms to promote more lawyers to the partnership in spite of political and economic uncertainties.

Bird & Bird, CMS, DLA Piper, Fieldfisher and Clyde & Co all announced that their 2019 rounds were the largest ever for the firms, while Simmons & Simmons also made up its largest cohort in more than a decade.

Other firms besides Slaughters to have made up fewer partners this year include Ashurst, Pinsent Masons and Hogan Lovells, which all made up bumper rounds last year with Hogan Lovells, as well as Addleshaw Goddard. The latter two firms made up just one less partner apiece than last year.

Several market executives put the bumper rounds down to a need for firms to maintain a strong pipeline of impressive juniors.

Jomati Consultants principal Tony Williams says: "I think there is, despite all of the uncertainties in the world, a 'let's get on with things' attitude in the market at the moment. Despite those uncertainties, whether they be caused by trade wars or Brexit or whatever else, the global legal market has been pretty robust. I think as a result there is a good level of confidence.

"There's an element to this of getting your talent pipeline going or you'll lose good talent, so that's an issue for some firms. Given the profile of a lot of these firms, they're also probably trying to make sure they're addressing succession issues.

"They realise they've got to motivate good people and show that although the line to partnership has gotten longer, there is still a good chance of getting to it."

Simmons & Simmons managing partner Jeremy Hoyland says the firm's bumper round could be attributed to the unusually high number of quality candidates who were put forward for partnership this year, but adds that the firm "didn't really have a strategic reason for doing this".

With regards to the wider market's motivations, however, Hoyland says: "I think it might be true to say that there was a bit of a build-up after a couple of years; I think we and some others made up fewer partners and therefore this year may be a result of pent-up demand. You also get to the point where you think: 'If we don't make these good lawyers up now, we're going to lose them.'"

DLA Piper global co-CEO Simon Levine adds: "Looking at the global economy, despite all the uncertainties, and maybe even because of those uncertainties, it has been pretty robust. If I look at how we're doing towards the financial year end, it looks like we could be having one of our strongest years.

"I think that in turn clearly reflects in our partner promotion numbers, because it tends to be the sign of confidence for a partnership when there's a good pipeline."