"Politics works on a five-year timescale, which is not the timescale you are working on," she said. "Ministers and officials change all the time and you have to start from scratch with the next one. Also, individuals and organisations fail to cooperate with others who have similar or overlapping aims."
But she urged: "Take every opportunity to see ministers, and not just the obvious ones. You won't have long so get your key message over first. Keep it short and snappy, then give them bullet points at the end.
"On a topic like invasive pests or tree maintenance, show that your point is in their department's financial interest - you are more likely to be listened to. This also goes for civil servants and local authorities. Also, respond to parliamentary select committees so you get your views on the record."