“It is beautiful,” said Craig ab Iago, Gwynedd council’s cabinet member for housing. “But there is an emergency here, a massive wave of a problem. It’s out of control.”

That emergency is the number of homeless people, which has increased in Gwynedd by 47% in the past two years. “It’s hidden. You don’t see people sleeping rough,” said Ab Iago. “But people are sleeping on sofas, in hotels, in bed and breakfasts, in vans. It’s immoral that some people have a second home here while others don’t have one.”

Gwynedd council’s Plaid Cymru-controlled cabinet this week voted for council tax premiums to be raised to 150% next year and the £3m raised be used to tackle homelessness. The full council, which is controlled by Plaid Cymru, will make a final decision next week.

Council tax premiums on second homes in Gwynedd are currently set at 100% and the discussion has tended to focus on whether this is having any impact on the housing sales market. The rationale for introducing the premium is to free up homes for local people, to stop the hollowing out of communities, which affects the viability of the Welsh language.

But the council is now arguing that another vital issue is the impact the number of second homes is having on the rental sector. People who cannot afford to buy are renting, so the number of properties available is shrinking and homeless figures are soaring.

High summer is here so let’s all go down to the beach. Family seaside houses have flung open their windows and picnics are being made. Children are gathering sand between their toes and collecting shells. Tide tables are being studied and rockpools plundered. What price do we place on properties that can offer all this – plus swimming, surfing, sunbathing and sailing?

Despite all our worries about the stability of the market and last winter’s storms, the answer is that we value these properties more highly than ever. The latest Knight Frank waterfront index, given exclusively to The Sunday Telegraph, shows that houses beside water are now worth an average of 60 per cent more than their counterparts inland, which is 11 per cent more than at the same time last year.

The wild cliffs, coves and sailing havens of the South-West exert by far the most powerful pull on those with money to spend. A house by the sea here can command a premium of up to 75 per cent, which is 17 per cent more than last year, creating a new seaside property superclass.

The seaside resorts of the South-East follow, with a premium of 44 per cent. East Anglia, with its creeks, marshes and rustling reed beds, comes next, at 41 per cent. In Scotland, the premium is 31 per cent, and in Wales 27 per cent.