Some messenger firms in London run a reward system for clients.Usually along the lines of each time you pick up a job the firm gets a stamp from the messenger, x-amount of stamps means a bottle of posh wine or a meal for two-etc.Also when you've built up a base of regular cients look at where they are mostly sending stuff and market hard to get that buisiness.I can't stress how important that is.The good firms in London are the ones that have a list of clients on their books that all do business with each other.Good luck!!!