I took this picture at my neighbor, on their fence.
According to my book  "500 Popular Tropical Plants";
Allamanda cathartica, also called "Golden Trumpet Vine".  

This vigorous climber, fast growing to 4.5m, bears large, yellow, trumpet-shaped flowers to 15Cm across.  

It has whorls of lance-shaped leaves and makes a luxuriant cover for walls and strong fences.  

The flowers of 'Hendersonii' are yellow with white spotted throats.

20 June 1999