For many, many months, the attorney general has been sitting on a decision on whether to launch a corruption prosecution over a large arms deal.

Figuratively, the file relating to the decision appears to be gathering dust. One supposes that from time to time Geoffrey Cox has opened the file and looked at it. He may have even discussed its contents with his aides.

The decision that has yet to be announced by Cox (and is now even less likely ahead of the general election) involves a politically contentious mix of alleged corruption, a large company in Britain and a prickly Middle Eastern ally.

The UK’s anti-corruption agency, the Serious Fraud Office (SFO), submitted a formal request to the attorney general to launch a prosecution in what is known as the GPT case.

The attorney general’s department will not say exactly when. However, sources with knowledge of the case say the request was submitted at least 18 months ago and could have been dated as long ago as November three years ago.

It concerns allegations that GPT Special Project Management, a UK-based subsidiary of the European aerospace group Airbus, paid multimillion pound bribes to secure a military contract with Saudi Arabia. The company is accused of using illicit payments and gifts totalling at least £14m to win a £2bn contract to provide communications and electronic warfare equipment to the Saudi national guard.

For decades, the UK authorities did little to enforce the law against this kind of bribery

The allegations were brought to light in 2010 by a former GPT employee, Ian Foxley. When he was about to blow the whistle, he fled Saudi Arabia overnight fearing that his life was in danger.

The SFO started its investigation as long ago as 2012. Its request to prosecute originally went to Jeremy Wright, Cox’s predecessor (Cox assumed the attorney general role in July 2018).

That the SFO submitted the request suggests its investigators believed there was sufficient evidence to bring charges. Technically, the attorney general is required to give his consent to a prosecution brought under the relevant legislation – the Prevention of Corruption Act 1906.

The delay in making a decision speaks to a deep malaise: suggesting that Britain is simply unwilling to prosecute major companies that are accused of paying bribes to foreign politicians and officials.

For decades, the UK authorities did little to enforce the law against this kind of bribery. Declassified papers show that in the 1970s, Whitehall officials facilitated the payments of backhanders to secure arms contracts around the world. There is a history of bribery in arms deals between Britain and Saudi Arabia.

The anti-bribery law was strengthened in 2010. But even since then there have been few prosecutions, as a House of Lords committee noted this year.

Given the low level of prosecution, it appears to be a low risk for corporate executives when they are contemplating bribing well-connected foreign politicians with influence over which company should be awarded a lucrative contract.

‘In 2006, Tony Blair’s government abruptly terminated an SFO investigation into another Saudi arms deal.’ Blair with the Saudi foreign minister, Prince Saud al-Faisal, in July 2005. Photograph: Stephen Hird/REUTERS

The shadow of a past corruption scandal looms over the attorney general’s office as the file from the SFO asking to initiate prosecutions in the GPT case remains unanswered. In 2006, Tony Blair’s government abruptly terminated an SFO investigation into another Saudi arms deal.

Back then, investigators at the SFO had been delving into alleged bribes to members of the Saudi royal family in the notorious al-Yamamah deal. BAE, Britain’s biggest arms company, had been accused of paying huge sums to land the deal.

As the SFO investigators appeared to be close to securing vital evidence, Saudi royals threatened to withhold key intelligence about jihadi terrorists from the British government. The threat worked, and the SFO investigation was closed down.

The termination of such a high-profile investigation damaged Britain’s reputation at home and abroad for tackling corruption.

The decision in front of Cox – and whoever becomes attorney general after the December election – could turn out to be a rerun of the BAE scandal. Susan Hawley, executive director of the organisation Spotlight on Corruption, has warned that the decision is a “key test of whether the UK has moved on from the BAE scandal and whether the SFO can tackle politically sensitive bribery cases”.

The biggest danger for the British government, however, is that a trial could reveal that the UK Ministry of Defence (Mod) was complicit in the alleged corruption.

The GPT arms deal was administered as part of an official (and highly secretive) agreement between the UK and Saudi governments. It meant that for years, payments, however large or small, made under the deal were approved by the MoD.

A court case may show that the MoD allowed substantial payments to dubious beneficiaries to be made even though there was no commercial justification for them. It would be appealing for any defendants to cite any such official connivance at a trial as they sought to clear their own names.

Key to that would be sensitive confidential documents held by the MoD concerning such payments. The MoD declined to comment when asked if it had refused to disclose documents to the SFO during its investigation – but staff were reportedly interviewed by the SFO during its investigation.

The attorney general’s long delay in making a decision in the GPT case has already undermined Britain’s reputation for tackling corruption. Blocking a prosecution altogether would, in the eyes of many, damage it further.

Anti-corruption prosecutors should be entitled to believe that the attorney general would back them up when they sought to tackle graft – rather than retreat in an all-too-typical British establishment cave-in.

It would also be a hammer blow for Foxley, who risked a great deal to expose corruption.