The correspondence, dated 18 October 2011, is from a staff member at one of the country's leading medical suppliers, Fit4Sport Limited, to Dr Richard Freeman, the former chief medic at British Cycling and Team Sky.

It shows that five months passed between the testosterone gel arriving at their headquarters and Freeman receiving confirmation it had been delivered in error.

Following a General Medical Council (GMC) investigation, Freeman faces an allegation that he ordered the banned drug in May 2011 to administer to an athlete to boost their performance, then lied to conceal his motive for the order.

Testosterone is outlawed by the World Anti-Doping Agency.

Freeman's case will be heard next month at a misconduct tribunal that threatens to cast another shadow over the country's most successful sport, following a series of controversies.

The medic has also been charged with contacting Fit4Sport to ask for confirmation that the order was sent in error to Manchester's velodrome - home to Team Sky and British Cycling - despite knowing this had not taken place.

Freeman is also alleged to have lied to UK Anti-Doping (Ukad) investigators in February 2017 by stating the testosterone had been ordered for a non-athlete member of staff.

The email

BBC Sport can reveal that on 18 October 2011, a member of staff at Fit4Sport wrote an email titled 'Testo Gel' to Freeman, telling him that they could "confirm that I have now received back the Testogel 50mg pack of 30 sachets which we sent in error to you".

It continues: "This will be destroyed on our premises. Apologies for any inconvenience this may have caused you, we will revise our procedure to ensure incorrect pharmaceutical products are not shipped out again."

The email from a member of staff at Fit4Sport Limited to former British Cycling and Team Sky doctor Richard Freeman

The background

In March 2017, Team Sky's then medical director and psychiatrist Dr Steve Peters told the Sunday Times he had immediately been made aware of the delivery of testosterone on 18 May 2011, but was told by Freeman that the delivery was made in error.

Peters said that was confirmed by the supplier by phone that day, and that he asked Freeman to send it back and to ask for written confirmation from the supplier that it had been a mistake.

Peters said he was shown this and was satisfied it had been an administrative error so did not inform team boss Dave Brailsford.

It is now known that the written confirmation was not sent by Fit4Sport to Freeman for a further five months.

In its terms and conditions online, the company says that medications are "non-returnable unless there is a discrepancy due to supplier error", and that they must then be returned "within 3 working days".

On its website, Fit4Sport claims to be "the leading sports medical supplier within professional football and rugby league", with a "strong presence" in cricket and with national squads for various governing bodies.

In pre-hearing information published by the Medical Practitioners Tribunal Service, it is claimed Freeman's "motive for his actions, in respect of the untrue statements and communications with Fit4Sport Ltd, were to conceal his motive for placing the order".

Fit4Sport told the BBC it would not comment while the GMC proceedings were ongoing.

In November 2017, British Cycling announced its intention to sever ties with Fit4Sport because they said the company - along with Freeman - had not co-operated with their investigation.

The company insisted it had complied with requests from the GMC and Ukad.

Freeman, the doctor who received a mystery medical package for Sir Bradley Wiggins in 2011, is also accused of "inappropriately" providing medical treatment to non-athletes and failing to inform three patients' GPs of "medication prescribed and reasons for prescribing".

The GMC also claims that Freeman, who resigned from British Cycling in October 2017 because of ill health, "failed to maintain an adequate record management system".

He denies any wrongdoing and told BBC Sport in July that he would "clear everything up" over the testosterone delivery after the GMC investigation.