I've done Goswell Road twice (since the good old days of India House), as I too prefer to do it in person.

Once I did it as an express business visa, and just pitched up in the morning without appointment and had my passport back late that afternoon.

The second time I did it by the normal service and it took three days.

On both occasions, I had filled in the forms online, had scrupulous documentation, and the correct sized photos.