The sea used to come up directly to the cliff and there wasn't the wide strand we know today. Erosion of the soft sandy cliffs was a huge problem and there was a series of storms in the early 1900's that cause severe erosion and that threatened the expensive houses built on the top of the cliff. A series of groynes were built to slow the action of the waves and to encourage the deposit of sand. As the groynes were built out, they didn't extend down to Pakefield and the houses on the cliff there did eventually fall into the sea as the waves undermined the cliffs.
The groynes added some sand, but it wasn't adding it fast enough and so a concrete wall was built with a walkway or promenade was built along the length of the cliff, ending even with Kensington Gardens. You can easily see the end of the first section of promenade today. I think todays beach visiters would be surprised at the height of the first wall and how narrow it was. At first there were no permanent beach huts. Early visitors either used tents for privacy or bathing machines.
The paths from the top of the cliff and the Promenade were landscaped and properly engineered with stone walls and handrails. Across from the Victoria Mansions Hotel there was a lovely overlook with a covered viewing room where tourists could stop for a cup of tea. You'll see many, many postcards that feature the room and it was a real loss when it was removed.
I don't have any photos of the lower promenade during WW2. The area was covered with barbed wire and defense and was off-limits to civilians, especially in the early war years when there was a high threat of invasion. As soon as it was permitted, tourists returned.
It's not until the 1970's that we start to see the wide beach we have today.