Lt Col Lesley Wilde from the Army’s London area headquarters, where he is based, said he is on course to complete the swim in 15 hours meaning he should be stepping onto the French shore around 6pm.
Capt Grantham oversees training of all mounted units, including the Household Cavalry Mounted Regiment and The King’s Troop Royal Horse Artillery, but suffered mental ill health after the break up of his marriage and moving away from his family.
A colleague noticed a change in his behaviour and encouraged him to open up and seek help.
Captain Grantham hopes to break down the stigma of mental health among men, encourage those experiencing mental health issues to come forward and seek help at an early stage, as well as urging others to offer support if they see something wrong.
All money raised from the swim will go to the Royal Artillery Charitable Fund to support Gunners dealing with mental illness, as he used to be in the King’s Troop Royal Horse Artillery and remains a part of that community.
The swim happens to be on World Suicide Prevention Day, which is particularly focussing on overcoming men’s mental health issues.
Lt Col Wilde said in an update: “He is having a bit of an issue with his shoulder that has slowed him down a bit, but he is keeping up his stroke rate.”
She explained that on a map, his swimming route is “shaped like a saxophone”.
“He is quite close to the French coast, but because of the tide he has to swim south, then north again when he is already tired. It is only 21 miles across from Dover to Calais but he will be swimming 27 miles.”
He is being cheered on from a pilot boat by friend and Army Welfare Officer Maj Nigel Mudd, who helped him open up about his mental health problems originally.
The pilot boat helps to safely navigate Capt Grantham through the busy shipping lanes of the Channel, dodging container ships and ferries passing within a few hundred yards, but all on radar.
Lt Col Wilde said all that could be seen of the swimmer was his head torch in the pitch black of the early morning and there were other support boats in the distance with other swimmers doing their own cross Channell attempts for different causes.
Although unassisted, the support crew have been allowed to toss a water bottle on a line out to Harry who grabs it to take on fluids while treading water for a few seconds before pressing on.
Talking about the reasons for his swim, Capt Grantham says: “Although the NHS and Defence Medical Services’ mental healthcare services are of a high standard and relatively easily accessed, many choose not to seek help. This may be due to the effects of stigma, either due to the personal meaning attached to help-seeking, or due to a wider concern about career progression and/or involvement of medical professionals.
“Those around me would not have been able to tell that my behaviour was anything other than normal.”
In his case the Army Welfare Centre provided “invaluable” support, enabling Harry to get well again.
He was drawn to swimming the English Channel by the incredible mental challenge that it offers.