In her first interview in the job, Ruth Evans, chair of the Independent Parliamentary Standards Authority [IPSA], said the public now expects “equal opportunity employment” in MPs’ offices.

Around 150 MPs – close to one in four – have a family member working in their office, while a number of prominent politicians have faced complaints about their arrangements.

Currently MPs face few limits to hiring partners or children. They are limited to hiring just one at a time and must publicly declare the situation.

“We would want to see the best possible person for the job being recruited in order to provide public value for money.

But Ms Evans hinted that when a consultation ends later this month she will decided to tighten the rules so MPs in the future must prove other better candidates were not available.

“It is a controversial area. On the one hand, public expectations have shifted and there is an expectation for equal opportunity employment. On the other hand, you do have MPs who have specific requirements,” Ms Evans said.

“It all comes down to what the job is and could we define more clearly what the responsibilities and roles are.

“Because it may be that if you can more clearly define specific roles, the answer becomes apparent as to who can take on that role.

“We would want to see the best possible person for the job being recruited in order to provide public value for money. That’s the key.”

Earlier this summer, Ms Evans became only the second ever chair of the IPSA, a watchdog created after The Telegraph’s investigation into MPs’ expenses.

During her 35-year career she has helped regulate the police, lawyers, doctors and broadcasters as well as chair two independent inquiries into healthcare, before beating around 30 rivals to get her new role.

“This isn’t about regulation, this is about encouraging them to account for the work that they’re doing in order that their constituents can be reassured.

Ms Evans is urging MPs to publish a yearly explanation about how their expenses are spent so voters better understand what is being funded.

“The more that MPs can tell their constituents how they use the public’s money and what they do in their jobs, so much the better,” she said.

“It makes sense for MPs to provide as much information as they can. We don’t want to burden them with excessive regulation.

“This isn’t about regulation, this is about encouraging them to account for the work that they’re doing in order that their constituents can be reassured.”

The first ever “annual account of expenditure” by MPs will be published in November and is designed as a way of them to get on the front foot.

For example MPs could explain how many constituents’ cases were dealt with from the salaries paid to staff or explain that unusually high office costs came only because of a change of address.

“MPs should be paid a fair wage for a job and in return MPs, in Ipsa’s view, should be accountable for the work that they do,” she said.

Ms Evans also defended allowing MPs to claim for first class travel, saying: “There’s no issue here because they only take first class travel if they can get it at the same rate as second class travel by booking ahead.