Looking for boulder clay on Walney Island

I'd heard that Walney is made of glacial deposits. Looking on the beach at Biggar Bank, I noticed a lot of pebbles made of rocks from further north. Then I noticed that the source of the pebbles appears to be the crumbling bank behind the beach. But this doesn't look like the glacial deposits I've found at Boggle Hole on the east coast and at St Bees. There the low cliffs are of more more clay like stuff with quite angular samples in. Here the rocks look like normal beach pebbles. I'm guessing that whatever the original origin of these pebbles, they have been in the sea previously. Perhaps an older shingle bank was more recently covered with vegetable matter than laid down top soil and that it is now eroding. Since these pebbles are not angular, I don't think this is a glacial deposit.