Jardine Lloyd Thompson Group has cut its 2015 profit forecast after a shake-up in Britain's pensions market hurt one of its key revenue drivers, sending its shares down.

The insurance and reinsurance broker warned that group profits would be hit by a third quarter slowdown in its UK employee benefits business, partly due to "uncertainty created by government-led changes to the UK occupational pensions market."

Full year revenues in that part of the business are expected to fall by a mid-to-high single digit percentage figure from 2014.

Trading profit for that division will be in the low to mid-teens in millions of pounds, JLT said.

Recent British pension reforms mean people aged over 55 no longer need to use their pension savings to buy an annuity, which gives a fixed income for life. Instead, they can either invest in other savings products or just spend the cash.

Changes to commission payments introduced following a recent British review were also having a "greater impact than anticipated" on trading profits, the company added.

The changes force financial advisers to charge clients a fee for their services, rather than being paid commission by asset managers, reducing the chances of firms paying higher commissions to have advisers push their funds.

Shore Capital analyst Eamonn Flanagan said he expected JLT's 2015 full year profits to fall by around £12 million, around seven per cent, to £168m.

Panmure Gordon & Co analyst Barrie Cornes changed his rating to 'hold' from 'buy' following JLT's statement.

Slower growth in the UK pensions business was partially offset by profit growth in the firm's risk and insurance units, lower net investment spending in the United States and cost reduction initiatives.

"While the recent performance of our UK Employee Benefits business is clearly disappointing, we are confident of returning this business to long-term growth," JLT group chief executive Dominic Burke said.