Hi Deemonee, greetings from Sydney.
Re 4d, I think it's because the answer is a proper noun. He's used the same thing in 10a.
In 25a, the def. is 'take a gander' so it's a homophone of '(h)ighball', how a cocktail would be pronounced in the East End. Possibly missing a homophone indicator, though that could be implied by 'in East End'