Archies jumping to conclusions IMO, Cornwall had 1000s of bronze age settlements. All were mining tin & copper. The safest way to have moved from cornwall towards Dover would have been by sea along the coast line.
There would have been zero need to travel to mainland Europe to get either tin or copper.
Cornwall has a big history of tin mining, tin mines were busy right into the 20th century, infact many of the Cornish gold and tin miners later became California 49ers.
Had you have been trading copper and tin from cornwall to say somewhere along the south coast the safest route avoiding places like Bodmin moor would have been to hug the coast line.
Back then the A303 which runs from london to lands end and passes stone henge and through Bodmin moor was not there. The moor had 1000s of bronze age settlements.
In any case these archies are making assumptions about the size of the boat used, it could have been 6ft long and had 2 guys in it and simply sunk close to the shore line.
If they can show a single reason that Bronze age Britons would have needed to bring copper and tin from Europe I will listen.
Nonetheless it is a bronze age wreck so in that respect it is interesting in itself and really does not require the completely unproven atlantic/channel crossing story involved.
Maybe the bronze age britons were not mining tin in cornwall after all, perhaps they were building the first Euro tunnel
