Finally managed to bodge my way around the problem, what I think has happened is a part of the rubber diaphragm has lodged between the lever piston and reservoir and blocked the flow, I got around this by bleeding it directly through the hose where the lever attaches and then filling the lever with fluid and carefully putting it back on, I then filled the reservoir and tried the brake and it's working again, better than it was before.
Massive bodge but oh well it works, thanks for all the advice.
Tom.