If experimenting with the tilt of the saddle doesn't help, you might look into a Selle An-Atomica, which is very similar to a Brooks, but with a cut-out. Search on Selle An-Atomica in this forum and you'll find that several people have posted their experiences.
But I'd try tweaking the tilt slightly, first - try tilting the nose down just a couple more degrees. If you don't have a micro-adjustable seatpost, you can cut a little piece of metal out of a can and use it as a shim (be aware that it will compress over time and you will have to re-adjust every few months - but it's cheaper than a new seatpost ).