Although some who have posted here say they did not need to cold-solve the majority of clues, I reckon I only made much headway once I had solved about 75%. There are posts here that can help if you want to read through them all. Solving both 13a, 16a, 24a, 25a, both 5d, both 18d and entries at 1d, 5d, 13a, 20a and 23a were my main ways in. Once you have the grid filled, the end-game is easy, so that's not the reward endgames sometimes are, but in this case it can help if you are missing the odd letter in one of the circled cells.
It's certainly one of the hardest Listeners I've come across.