GRAHAM Wynne, chief executive of the Royal Society for the Protection of Birds (RSPB) will address a mass anti-airport meeting in the heart of the threatened Cliffe marshes this afternoon.

The meeting starts at 4pm in the Northward Hill RSPB reserve, which will be used as a natural amphitheatre overlooking the area which would be covered by the proposed airport.

An RSPB spokesman said: "As well as key speakers, the community will be invited to gather en masse with their banners. There will also be a barbecue and picnic and wildlife-based activities for all the family.''

Other strands of the anti-airport campaign are urging people to keep up the pressure and write protest letters to politicians. The Action Group for No Airport at Cliffe is urging people to send letters to Prime Minister Tony Blair, Transport Secretary Alistair Darling, Medway Council, local MPs and MEPs.

Co-founder Ann Parker said: "Petit-ions don't carry the same weight as letters.''

The organisers want writers to stress that they don't want their lives blighted by an airport with its exhaust, noise and light pollution and are against the wildlife and countryside being destroyed.

Letters to Mr Blair should be sent to Mrs Parker's home, 34 St David's Way, Alhallows ME3 9PW, as her group plans to take them to 10 Downing Street. Letters to Mr Darling, Mr Marshall-Andrews, Mr Clark and Mr Shaw can go via the House of Commons, London SWIA 0AA.

Others addresses are:

*Further Development of Air Transport, South East and East of England, Dept of Transport, ROOM 1/28C, FREEPOST LON 17806, London SWIP 4YS.

*Dr Richard Simmons, Director of Development and Environment, Medway Council, Compass Centre, Chatham Maritime, Chatham ME4 4YH.

*James Proven MEP, Middle Lodge, Barns Green, Horsham, West Sussex.

*Roy Perry MEP, Tarrants Farmhouse, Maurys Lane, West Wellow, Romsey, Hampshire SO51 6DA.

*Peter Skinner MEP, 99 Kent Road, Dartford, Kent DA1 2AJ.

*Mark Watts MEP, Euro Office, 29 Park Road, Sittingbourne ME10 1DR.