STENA Sealink has cut its summer cross-Channel fares by 20 per cent - with strings attached. You have to book by 2 July through the AA, Co-op Travelcare, AT Mays, Lunn Poly or American Express - or direct with the company, on 0233 647047. The saving on fares to Calais, Dieppe and Cherbourg applies only if you take out travel insurance; a family of four sailing Dover-Calais in July for a fortnight would pay pounds 218.45 with the cheapest insurance option - only pounds 1.55 less than the regular fare.