The lowest paid equity partners at at least five UK top 50 firms take home less than 20% of what the top equity partners receive, Legal Week research has revealed.

Figures provided for Legal Week's annual UK top 50 rankings show CMS, Freshfields Bruckhaus Deringer, Gowling WLG, Watson Farley & Williams and RPC all paid the partners at the bottom of their equity less than a fifth of what their top earners received for 2015-16.

Thirty UK top 50 firms disclosed top and bottom of equity figures for the research and, of those, CMS has the biggest pay gap in percentage terms, with the firm's top earner receiving 10 times the pay of the lowest earner. Figures provided by the firm showed that the highest paid member took home £1.126m last year, compared to just £115,000 at the bottom of the equity.

In a statement, CMS – which has 61 offices in 36 countries – says: "The gap is a reflection of our global reach and large geographical spread, and the economics of each individual marketplace in which we operate."

Average profit per equity partner (PEP) at the firm was £443,000, meaning the highest paid member received more than two and a half times that amount.

Freshfields has the next biggest discrepancy between highest and lowest earner, with the firm's top earner receiving more then £2m while the lowest paid partner took home just 16% of that – £335,000.

The £335,000 bottom of the equity figure represents just 22% of the firm's 2015-16 PEP, which at £1.47m was the second highest in this year's UK top 50 rankings.

At the start of this year, Freshfields moved some partners to a lower lockstep ladder as part of a push to ramp up profitability. The firm first introduced a second-tier lockstep ladder running from 10-30 points – compared with the standard 17.5-50 points – in late 2013, but it is understood that its use has increased significantly this year.

Former Clifford Chance managing partner and Jomati Consultants principal Tony Williams says  these kind of discrepancies in pay are simply part of the environment partners must accept.

"This is a reflection of the reality of working in a very competitive market, particularly with the influence of US firms. Firms just recognise they have a limited profit pot – if they are overpaying someone they are underpaying someone else," he explains.

Is it better to reward good people who feel under-rewarded, or others who are complaining life is hard?

Williams adds: "It is a challenge – you can use different metrics, make sure you are encouraging and keeping to key principles, but let's get real – if you want to be at the top of the equity at a major magic circle firm you have got to have a £4m-£5m practice. If you cannot deliver that you either have to move down or move out – that's business in a high performance culture. You have to pick the lesser of two evils – is it better to reward good people who feel under-rewarded, or others who are complaining life is hard?"

Elsewhere, Gowling WLG's bottom earner took home £148,000, just over 18% of what its top earner received. The top of the equity figure of £815,000 is more than twice the firm's PEP of £379,000.

At Watson Farley & Williams, its lowest earner took home 17.5% of what its highest paid partner received, with the firm's top earner taking home £1.2m, compared to £210,000 at the bottom of the equity.

Watson Farley co-managing partner Chris Lowe says: "We widened our equity this year and the figures reflect this. We believe a wider range is important, especially for an international firm with equity partners spread across multiple jurisdictions, as it prevents exchange rates being a barrier for talented young partners to join our equity and accommodates high performing partners in our lockstep."

Completing the five firms that paid their lowest earner less than a fifth of what their top earners took home was RPC. The firm's best paid partner netted just over £1m, while its lowest earner took home £200,000 – 55% of the firm's £362,000 PEP figure.

In contrast, a handful of UK top 50 firms have a much narrower equity spread, including three that pay their lowest earning equity partner at least 50% of the firm's top of the equity figure – Mills & Reeve, Blake Morgan and Holman Fenwick Willan.

Mills & Reeve, which this year placed 45th in the UK top 50, paid its highest earner £431,000 in 2015-16, while its lowest earner received 68% of that amount – £294,000.

Blake Morgan and Holman Fenwick Williams both have bottom of the equity figures standing at 50% of their top of equity figure, while a further eight firms – including magic circle players Allen & Overy and Linklaters – paid their bottom of the equity partners at least 40% of their top of the equity figures.

• Click here to view Legal Week's 2015-16 top 50 UK table