Top law firms have paid MPs hundreds of thousands of pounds for consultancy services since the start of last year, the latest parliamentary Register of Members' Financial Interests reveals.

The register, which was released last week and contains details of payments to MPs up to 9 March 2015, also outlines lucrative speaking engagements for several MPs including ex-Chancellor Alistair Darling and former universities and science minister David Willetts.

Some of the highest fees were charged by Conservative MP for Huntingdon Jonathan Djanogly, who has received £5,000 each month between February and December 2014 from King & Wood Mallesons (KWM) for consultancy services.

In August 2014 he performed four hours of work for the firm – one hour less than his quietest month in 2013 – equating to an hourly rate of £1,250.

Djanogly's busiest month since the beginning of last year was September, when he did 15 hours work for the same payment.

A spokesperson for KWM said the firm "engaged with consultants because they support the business to continually improve and develop".

She added: "We have a longstanding relationship with Jonathan as he is a former partner of our firm, and, like many of our consultants, Jonathan enriches our firm."

Meanwhile, Reed Smith paid Harborough MP and barrister Sir Edward Garnier QC £3,841 for approximately four and a half hours of work in April 2014.

DLA Piper also paid £160,000 to the former solicitor general "for legal services provided" since last January.

Stephen Phillips, the MP for Sleaford and North Hykeham, has acted as a QC in private practice for at least seven firms, including Hill Dickinson, Reed Smith and Holman Fenwick Willan, since last January.

One of the lowest hourly rates was charged by Jake Berry, Conservative MP for Rossendale and Darwen, who was paid £7,500 by Squire Patton Boggs between August and February for "advising on client services, business development and other specific matters".

He clocked up a total of 96 hours of work over the period, equating to an hourly rate of just over £78.

Asked why Berry's rate was far lower than his peers, a spokesperson from Squire Patton Boggs said that the firm did not publicly discuss its contracts with consultants "as a matter of policy".

The highest hourly rate was charged by Conservative MP for Congleton Fiona Bruce. In January she received £64,206 for 11 hours of work at Fiona Bruce Solicitors, the law firm she founded, a rate of almost £6,000 an hour.

Several MPs also made lucrative speaking appearances at law firms.

White & Case paid out more than £10,000 to Alistair Darling for speaking at an event in November. Darling was the top speaker at the headline event in the firm's Autumn seminar series.

This was followed by a fee of £1,700 paid to Darling in January for writing a feature in a forthcoming issue of the firm's client magazine.

David Willetts donated his £1,000 fee from Eversheds for speaking at the firm's pensions conference in December to charity, the register shows.

White & Case and DLA declined to comment on the fees. Fiona Bruce was unavailable for comment.