Gwiwer,
The sea wall at the the town end in Teignmouth i.e. the part from just west of the swimming pool was built with a concave profile. East of this the sea wall is either much less concave or flat.
On 5th February we were watching the sea at high water near the pier. The concave wall was returning the water well at most times with just the occasional (7th?) wave crashing over. The concave wall was constructed with a shelf as you mention but in places this shelf is now under a lot of sand. West of the pier the shelf shows whereas east of the pier it is buried.
Along the sea wall, the part that supports the railway, again it is a case of at times the shelf is visible and at times the shelf is covered. One of the photos I took last Monday shows the handrail that was put in place many years ago to help you step down to the beach from the raised ledge at the bottom of the sea wall. This handrail now vanishes into the sand, I am not sure how deep the sand build up is exactly.
Whilst watching the sea break over the railway sea wall, you could see that it was less dissipated by the sea wall shape than it had been by the concave wall in the town. Obviously these tides were high and the sea state much rougher than normal.
At present we cannot access the beach eastward of Sprey Point going towards Smugglers Lane, but in the past I have seen the beach in part of that area quite badly scoured and in one area you could see the sea wall footings exposed.
A friend who lives about 60-70 metres from the (concave) sea wall said that indoors on the night of the 4th he could feel the waves hitting the wall.
Cheers
LE