Two disused South Wales reservoirs proposed for a luxury housing project have been given a fresh chance to stay undeveloped after a judge backed their designation as a site of special scientific interest.

The ruling has "delighted" campaigners who have been fighting the plans to develop the area into housing, which was first put forward in 2002.

The strange thing is that if the banks of the reservoirs - which have been disused for some while – had not been kept mown, the rare waxcap mushrooms would have not colonised the site in the first place.

Developer Western Power Distribution Investments (WPDI) had planned to build 324 homes at the Lisvane and Llanishen reservoirs which were built in 1860 and 1880 and took the Countryside Council for Wales to the High Court in London to try and overturn CCW's designation of the reservoir embankments as a Site of Special Scientific Interest for their spectacular array of grassland fungi. 

In a 12 page judgement, Mr Justice Collins dismissed their claim, agreed that the site was of international importance for its waxcap fungi, and supported CCW’s notification.

Mr Justice Collins said: "There was ample evidence that the number of species made this an important site."

The decision has taken the magic out of WPDI’s plans and delighted campaigners but the judge added that SSSI status does not preclude development on part of the site and said the area could be reclassified if more important mushroom examples are found locally.