Ive had generally successful results doing the following.
Go to the chemist and buy an old fashioned erasmic shaving stick. They about 50p.
Rub it all over the top of the saddle till its got a good coating on. Scrub gently with a damp nail brush, wipe off with a damp cloth. Try not to get the saddle too wet. Repeat till its clean. Leave to dry then give it a good going over with rennapur or proofide. I prefer rennapur but i use both. Remember to give the underside a few coats as well. Fit on bike, put on black shorts and ride. Or if you haven't black shorts, get an old beret from the army stores and slip that on the saddle.
Hope this is of help.