By Janey Doyle
BBC News, Hampshire
It is May 1823, Cheesman Henry Binstead is onboard the Portsmouth-based HMS Owen Glendower.
With the West Africa squadron, the 26-year-old midshipman is on one of the Royal Navy's fleet of ships tasked to stop the trade of slaves, in the wake of laws to abolish the transatlantic trade.
Ch Binstead records in his personal diary: "Observed many large canoes, one of which I went in chase of, on my coming up with her the whole crew jumped overboard and I fear they have met a watery grave, these poor wretches were fearful we were going to make slaves of them."
West Africa squadron
Spanned 1808 - 1860s
Approx. 150,000 slaves were freed
1,600 ships were seized
Approx. 2,000 men died on the squadron
Later he adds: "I never witnessed a more horrid description than my messmates gave me of the wretched state they were in aboard, actually dying 10-12 a day owing to the confinement below all the men are in irons and women under them by a small petition."
His tales form a rare record of the Royal Navy's mission to stop the illegal transportation of slaves along the African coast.
The task began in 1808 but although the Navy's initial 50-year campaign ended, its interception and destruction of human trafficking has not.
'Why West Africa?'
Back to 2007, and HMS Enterprise is at sea off the West African coast.
At the time the UK is marking the 200th anniversary of the Parliamentary Act which led to the abolition of the slave trade, the crew's task involves updating maps of the coastline, some of which have not been updated since they were drawn up by Ch Binstead's colleagues.
In a blog, crew members recall why they are taking part in a research trip to that coastline: "Some have asked "Why West Africa"? Well the list includes, Commonwealth, collaborative work, the threat from piracy, anti-drug work, contributions to countering illegal human trafficking, offshore oil installation security..."
Countering illegal human trafficking falls under the modern Navy's maritime security operations.
Research ship HMS Enterprise is stationed off Nigeria
"Firstly, today's Navy is designed to fight warfare," Lt Cmdr Bill Lauste said.
"But as part of this, it enables it to conduct humanitarian relief - maritime security operations, to do with illegal use of the sea.
"We've always got ships in the Caribbean, West Africa, Mediterranean, Gulf, Horn of Africa etc - areas subject to natural disaster and on the manmade side ships have tendered assistance to boats loaded with people being smuggled."
"HMS Illustrious and HMS Scott tendered assistance saving many hundreds of lives."
The Navy's powers to stop and search were queried with the West Africa squadron.
"In the early days there was this fear, particularly from the American navy because obviously we were still in a period of semi-conflict and debate, this fear that if the Royal Navy had the power of right to search they would then just go and stop ships and interrupt their shipping and commerce," Deborah Hodson, of Portsmouth Naval Museum, said.
"In reality the Navy only ever stopped ships that they were allowed to stop through treaty, otherwise it would have been seen as an act of war - you couldn't just go and stop another ship and demand to search them for slaves or slave traders but it was a point of diplomatic debate."
The West Africa squadron, initially just two ships, expanded its patrol of about 3,000 miles of the African coast to about 30 ships. It had seized approximately 1,600 ships and freed the 150,000 Africans aboard. Just 10% of the estimated numbers involved in illegal trade.
Lt Cmdr Lauste reminds that the Royal Navy now "do not routinely go out to seek down/prevent illegal smuggling of people" but they will always assist.
"[The Navy is] rendering humanitarian aid to victims of smuggling, as and when we come across them, as they are victims, they are exploited," he adds.
Last summer, the Navy's flagship, Portsmouth-based HMS Illustrious intercepted a dhow in the Arabian sea.
"When we investigated it more closely it turned out there were 750 people which was a huge overload for a vessel that size, " Captain Bob Cooling said from the aircraft carrier.
The crew of HMS illustrious aided an over full dhow
"It's just not safe to have anything like that number of people on board I would say that 100 is the limit for that size of vessel - with 750 people it could capsize at anytime."
Two centuries after Ch Binstead's diaries, Lt Cmdr Ahmed Ajala, who served on HMS York, gives his own first-hand account of illegal human trafficking.
"East of the straights of Gibraltar we had to pick bodies out of the sea - after they were travelling to a Spanish island from Africa.
"These people were suffering and traffickers had left them at sea.
"The Navy will hand them over to the authorities, provide humanitarian aid and assistance."