The pipe is expected to discharge millions of cubic metres of floodwater, silt and algae from Loe Pool onto the historically important wreck, says local diver Mark Milburn, who has taken one of the few photographs of its remaining guns.

“The original overflow pipe from Loe Pool discharged 200m away from the Anson site but was damaged by falling rocks during winter storms,” says Milburn.

“Its replacement is being installed to discharge onto the bar above the main section of the Anson site, possibly covering it with shingle and silt forever.

“There has been no local campaign or complaints because it’s a flood-alleviation scheme, but both the Pool and Bar are SSSIs [Special Sites of Scientific Interest]. The MMO [Marine Management Organisation] said the pipe wasn’t a concern because it discharged above the waterline – which should wash some of that SSSI shingle away.”

HMS Anson was launched in 1781 as a 64-gun third-rate ship of the line but later converted to a frigate with 44 guns, 26 of them 24-pounders. Returning from a blockade at Brest in a storm in 1807, it found itself on the wrong side of the Lizard, in Mounts Bay. Each time it dropped anchor the cables snapped.

The captain decided to beach the Anson onto Loe Bar, the steeply sloping shingle bank between Porthleven and Gunwalloe Cove, but she rolled broadside onto it 20m from the beach. Some of the crew managed to reach safety by crawling along the mast, but between 60 and 190 died – the numbers were uncertain as some press-ganged survivors deserted.

Watching lines fail to reach the wreck made an impression on one local observer, Henry Trengrouse, who would later invent the rocket rescue apparatus and an early form of the breeches buoy.

The dead sailors, buried without coffins in unconsecrated ground, were among the last to be treated in this unceremonious way – the following year an Act of Parliament decreed that churchwardens should bury such bodies in consecrated ground.

Several of the 24-pounder guns have been salvaged over the years, with four at the entrances to RNAS Culdrose and Porthleven harbour and one outside Helston Museum, which contains other Anson artefacts and Trengrouse’s original rocket apparatus. Some of the other cannon were removed and scrapped.

“One of the 24-pounders that’s left quite often shows just a few inches above the sand,” says Milburn. “It’s believed that there are between 11 and 13 cannon still on site, as well as many other items concreted around the area. And it’s rarely seen, but eyewitnesses have reported seeing what appears to be a large ship, lying flat on the seabed.”

“Although the Anson is not currently protected, we’re aware of its historic interest, having identified it for potential investigation during our strategic assessment of early ships and boats,” Alison James of Historic England told Divernet.

“However, our initial assessment concluded that the Anson is broken-up, as it was subject to significant salvage, and that the presence of further buried remains to warrant investigation/protection have yet to be proven.

“In general terms, accumulation of sedimentary material over an historic wreck-site assists with its physical protection, ensuring that archaeological remains survive in situ for future divers to enjoy.”

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