Suella Fernandes. Image, Channel4, fair use.

Labour MPs are demanding a full investigation by parliament's expenses watchdog, IPSA, into the ''funding and activities'' of a group of hard-line Conservative MPs who have been branded a ''party within a party'' .

More than a quarter of a million pounds in official expenses has been claimed by a group of 40 Tory MPs for ''research'' carried out by the European Research Group (ERG). All the MPs are members or supporters of the ERG whose stated aim is a hard, uncompromised exit from the European Union.

The Tory MPs, including members of Theresa May's cabinet, have channeled the money to the ERG over the last five years, covering the period of both the David Cameron and May administrations.

Under IPSA rules, MPs cannot claim for research or work ''done for, or on behalf of a political party.''

Following an investigation by openDemocracy, the former Conservative minister, Anna Soubry, called the operation of the ERG ''a party within a party'' and stated that there were  questions over whether or not public money should be given to the group.

No accounts or membership list of the ERG is published, despite repeated requests from openDemocracy in recent weeks. During an interview with Channel Four News this week, the current chair of the ERG, the Fareham MP Suella Fernandes, refused once again to reveal who were members of the ERG and said that information was only available to the group itself.

Fernandes looked increasingly uncomfortable after she accepted that the ERG did take public money, but dismissed the suggestion that transparency of its activities should be automatic.

Labour MPs led by Steve Doughty have written to IPSA stating that the ERG has an effective 'secret' list of members and that the way it receives public money through the claims of some Tory MPs ''is significantly different from the funding that is used for other pooled research facilities'' including the policy research unit used by the majority of Conservative MPs .

The ERG's last chair was Steve Baker, who was promoted in June this year to a minister in the Department for Exiting the European Union. He is widely regarded as effectively in control of the 80 or so members of the ERG who this weekend are expected to back a public statement by pro-leave MPs demanding that Britain must be ''well and truly'' out of the EU by March 2019.

Baker is seen by many Tories on both sides of the European divide as capable of holding the government hostage over Brexit issues. If Downing Street begins leaning towards a softer Brexit or an lengthy transition with the UK still governed by rules from Brussels, the ERG is likely to be the front line of any revolt that could see May ousted as prime minister.

The Labour MPs want IPSA to clarify what funds are permitted to be claimed for and whether there should be greater ''transparency'' of the funding of ''closed pooled research services''.

The group also want IPSA to reveal the total amount of public money handed to the ERG through MPs expenses.

Clarification has also been demanded on the status of the ERG's senior researcher, Christopher Howarth.

openDemocracy revealed that details for who Howarth works for in the Commons, and the way he effectively runs the ERG as an independent organisation, do not to match the rules laid down by the Sergeant at Arms office. The Segeant's office is responsible for the administration and security of the Hose of Commons.

IPSA have also been asked to investigate who Howarth is currently sponsored by and whether or not he is located in offices inside the Palace of Westminster and on ''what basis'' is he working.

Full text of letter from Labour MPs, led by Stephen Doughty.

For the attention: Independent Parliamentary Standards Authority.

*^Allegations surrounding the funding and activities of the European Research Group**

You will be aware of allegations that have surfaced in recent days regarding the alleged use of IPSA funding claimed by a number of Members - it is suggested at least 40 - with total funds claimed for "research" in the hundreds of thousands, which is apparently being funnelled to the European Research Group, a hard-right, hard-Brexit grouping within the Conservative Party that has a restricted and secret membership.

You will note this arrangement appears to be significantly different from the funding that is used for other pooled research facilities such as the PRS, PRU etc. which are open to all MPs. The current Chair of the group Suella Fernandes MP has allegedly refused to provide a full public list of members.

Allegations have also been made about the use of Parliamentary facilities by Christopher Howarth who appears to be the senior official supporting the group.

Could you advise us as to whether:
- if IPSA funds are permitted to be claimed for research of this nature, what requirements exist around the registering of such claims, and the transparency required of the overall activities, funding and operations of closed pooled research services?
- what the total amount of IPSA funding claimed for the ERG or other "European Research" by Conservative Members has been in each of the last five years, broken down by the Member blaming it?
- whether the ERG or any of its staff are registered in any capacity that would allow them the use of Parliamentary offices, phones, passes etc.?
- whether Christopher Howarth is currently occupying offices provided to his sponsoring member Steve Baker, or whether he is located elsewhere in the Palace of Westminster and on what basis?

We look forward to your urgent reply

Yours sincerely

Stephen Doughty MP, Chris Bryant MP, Ben Bradshaw MP, Neil Coyle MP, David Lammy MP, Lead Supporters of Open Britain.