A few years ago I stayed at Langton House in Dorset, now owned by the Holiday Property Bond, but formerly a boys' school.

It was only a short stroll down the grassy slope to 'Dancing Ledge' where, cut into the rock and filled by the tide, there is a small bathing pool which was used by the school.

This Betjeman poem brings it all back to me.

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Dancing Ledge

HEARTS TOGETHER

How emerald the chalky depths
Below the Dancing Ledge!
We pulled the jelly-fishes up
And threw them in the hedge
That with its stones and sea-pink tufts
Ran to the high cliff edge.

And lucky was the jelly-fish
That melted in the sun
And poured its vitals on the turf
In self-effacing fun,
Like us who in each other's arms
Were seed and soul in one.

O rational the happy bathe
An hour before our tea,
When you were swimming breast-stroke, all
Along the rocking sea
And, in between the waves, explain'd
The Universe to me.

The Dorset sun stream'd on our limbs
And scorch'd our hinder parts{:}
We gazed into the pebble beach
And so discussed the arts,
O logical and happy we
Emancipated hearts.

John Betjeman

Dancing Ledge is part of the Jurassic Coast near Langton Matravers in the Isle of Purbeck in Dorset, England. The 'Ledge' is a flat area of rock at the base of a small cliff (a little scrambling is required for access). It is signposted on the South West Coast Path a few kilometres west of Swanage. A swimming pool was blasted into the rock for the use of local preparatory schools sometime near the beginning of the twentieth century. The one remaining school (The Old Malthouse in Langton Matravers) for which the pool was originally created recently arranged for debris, including several large rocks, to be removed, making swimming possible once again. The sea is also suitable for swimming, although it is deep right up to shore. This depth was exploited by local quarrymen in transporting Purbeck Limestone away from the area.
Dancing Ledge is so called because the stone cut out of it is the same size as a ballroom dance floor. The stone removed was transported by ship direct from Dancing Ledge, round the south coast to Kent in order to construct Ramsgate harbour.

(Wikipedia))