Most holiday accommodation on this tiny Danish island has already been snapped up for Easter, says the agency, and almost all of it by Germans. At the height of the summer season the German population reaches 100,000, compared with 35,000 Danish residents. Every day German families stake their claim to a patch of Fano's magnificent eight-mile beach, transforming the sands into a giant patchwork of brightly coloured windbreaks and towels. Above the dunes children play hide and seek in wartime bunkers.
"You'd find it hard to find a Dane on the beach in July," says Claus Thyssen, the letting agent. "In fact you'd never guess you were in Denmark at all. They love to come here. After all, we have this wonderful coast - and there are only 5 million of us and 80 million of them."
But no matter how early the Germans hit the beach, they are banned from owning any land or property on Fano. As long ago as 1959 Denmark passed a law preventing foreigners from buying summer houses. Unless someone has lived in Denmark and paid taxes for five years, summer houses are only for rent.
Since Denmark joined the European Union in 1973 it has been under constant pressure to abolish this blatantly "unEuropean" law, especially with the advent of the single market, upholding the right to free movement of capital and of people.
None the less, in 1992 the Danes won a special "opt out" protocol in the Maastricht Treaty allowing them to maintain their legal defence against German property ownership. But now the Danes see new evidence that Germans are trying to outflank them, by getting Danish relatives or friends to buy properties in their name. In a highly controversial legal action, 20 Germans have recently been accused by Danish courts of illegally buying property along the Danish coast, and have been given six months to sell up and leave.
The Danish interior ministry has instructed local residents to observe the movements of Germans and to report if they suspect any illegal property sales. An eye is kept on estate agents across the border offering Danish property for sale.
The Danes fear that negotiations to rewrite the Maastricht Treaty could bring new demands from Brussels for their protocol to be abolished. However, Denmark is not the only country which is increasingly worried by creeping German settlement. On joining the EU, Sweden, Finland and Austria all attempted to win Danish-style protocols to deter German land ownership, but were refused.
In Spain, the chief minister of the Balearic islands, Jaime Matas, recently called in the German consul to complain about the amount of property in Majorca being bought up by his countrymen and women, including the supermodel Claudia Schiffer. There is already one German resident for every six locals on the island, and a window poster campaign is demanding a halt to further settlement.
"Germans are buying up the island," said Mr Matas, "and they just won't integrate with local people and adopt our customs."
Austria is up in arms about the number of Germans buying property in the Tyrol, where in some resorts more than half the holiday homes are owned by Germans. The European Commission has launched a legal action against Austria after Vienna passed a law requiring anyone buying property in the Tyrol to seek a permit from the Tyrolean land authority.
Along the coast of Zeeland in the Netherlands, the Dutch are also seeking ways to halt the German advance. In the town of Westkappelle, where more than 10,000 Germans have bought holiday homes, outnumbering by five-to- one the 2,000 residents, local by-laws have been passed, making it harder for foreigners to buy property.
Even Germany's eastern neighbours are worried about incursions - the Poles are nervous about heavy German settlement around the picturesque Mazuria lakes. But nowhere is the German holiday migration so striking as in Denmark. The unspoilt beaches of Jutland have always been eyed with envy by the Germans, whose only coast is along the Baltic to the north. Even before the war Germans owned houses in Jutland, and they were back in the early Fifties, undeterred by possible Danish resentment.
"For the older generation who had lost people in the war, the German tourism was upsetting," says the agent Claus Thyssen. Other Danish residents simply complained that the German presence was pushing up prices and forcing out locals.
There are, nevertheless, some Danes who think the property laws are outdated and should be changed. Speculators count up how many summer houses could be built and sold off to Germans at a vast profit if the ban was lifted. Denmark's southern border, which has moved back and forth over the centuries, is becoming increasingly blurred as frontier checks are reduced, and keeping out German buyers is becoming pointless, say some.
The protectionist Danes, meanwhile, are often accused of hypocrisy by Germans. Many of the Danes who have summer houses in Fano, they point out, live abroad to escape Danish taxes.