Hi Paul, I will expand...

Like Chris has said by testing first you might get away with using Eco spotter. As we all know Eco contains alcohol which is brilliant at removing ink on leather, but can also remove tanning agents causing colour loss.
Isopropyl Alcohol (available in most pharmacies) is the product of choice for removing ink from leather as well as ethanol or isopropyl alcohol (rubbing alc).
I would steer clear of these if your unsure and go with a stick based cleaner.
As for products, LTT do some nice stuff or you could try Fenice products which dont get mentioned much on these boards, these guys have been producing leather cleaning products for 30 years and have a great range.
Mark