Green Park to Haymarket isn't that far, if it's not pouring with rain suggest a stroll, push down the road. Buses have become a nightmare for disabled passengers, you would think things have changed since the Paralympics, but not so. And having some difficulty myself in that department can testify that buses are not wheelchair user friendly. There is a space for one on most of the bus routes, but time and again it's taken by prams, and luggage... don't expect bus drivers to be helpful either,