The Conservative MP, who has represented the town in Parliament since 2005, has employed wife Jennie as his executive secretary for a number of years on a salary widely reported to be £45,000 per year.
In January Mr Bone’s romance with Corby and East Northants Conservative Association chairman Helen Harrison became public.
Mrs Harrison, a qualified physiotherapist, also works for Mr Bone as a senior Parliamentary assistant.
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Labour’s Andrea Watts, who was beaten by Mr Bone in the last General Election, said: “His relationship is his business but I think it’s wrong to employ a family member, let alone a partner as well.
“MPs get paid enough and the taxpayer is funding other expensive jobs for them.
“If I was elected [as MP] I’d be on about treble what I earn as a warehouse operative.”
Ms Watts, a councillor on Wellingborough Council, added that employing a family member is not allowed in the Labour Party and she felt a law should be brought in to stop it happening.
The salary for a non-London MP’s senior Parliamentary assistant is between £30,290 and £43,105.
The Northants Telegraph asked Mr Bone whether he employed his girlfriend before or after their relationship began, whether her job was advertised and whether he thought it was fair that the public was funding a job for both his wife and girlfriend.
In a statement, he said: “All of my staff are employed according to the Independent Parliamentary Standards Authority’s (IPSA) rules and regulations.
“All of my Parliamentary expenses are compliant with IPSA regulations.”
Mr Bone, 65, also failed to address whether HH stood for his girlfriend and JB stood for his wife in his expenses claims.
Between July 2017 and October 2017, train fares totalling £711.70 under ‘HH’ were claimed back in expenses.
A £66 Wellingborough to London return and £35 in London Underground tickets were also claimed back under ‘JB’.
There is no suggestion of anything illegal or any wrongdoing in Mr Bone’s expenses or staffing.
Mrs Harrison, an East Northants councillor who unsuccessfully stood for the Bolsover seat at the last General Election, also works as a senior Parliamentary assistant for Corby MP Tom Pursglove.
Her LinkedIn page says her responsibilities for both MPs cover “speech writing, preparing Parliamentary questions, media prep, writing articles, drafting Private Members’ Bills, research, complex case work and engaging with constituents”.
It says she has been in the job since June 2017.
Both Mr Bone and Mr Pursglove said they could not comment on Mrs Harrison’s ‘entirely separate’ employment with any MP other than themselves.
Speaking to The Sun in January, after he and his girlfriend were pictured leaving his flat, Mr Bone said: “My wife and I have been living apart for more than two years, during which time I have formed a relationship with Helen Harrison.
“Neither Helen nor I intend to make any further comment about this matter.”