It was singing most of the time but way up the wooded slope. After aboutt 15 minutes of this I decided to go to the bird rather than wait for it to come to me. This however didnt improve the situation. The sides were steep, overgrown and slippery and as soon as I got anywhere near to where the singing was coming from it then moved to somewhere else. This happened 3 or 4 times until I finally realised that this tactic was not working so I slid my way back down the hill, sweating and muddy and covered in undergrowth, to the amusement of the couple of dudes that had stayed put next to the layby. Well at least I tried! Luckily they hadnt got sight of it either. As well as doing its expected song it was also doing plenty of Chiffchaff type stuff also. See The Somerset Birder blog for an explanation of this.
As time went on the singing then lessened until it wasnt heard for some time, a cue to leave!
Went down to Porlock Bay for some lunch
Before heading off home we decided to have one last go for the Chiff. On arrival was greeted by some very excited people saying that they had just had it singing right in front of them but they hadnt seen or heard it again for about 10 minutes.
After another 15 minutes or so, the silence was broken by an impressively loud burst of singing Iberian Chiff. Eventually managed to get onto it in a leafy oak tree. It moved around continuously, calling a lot of the time. It kept high in the canopy but after lots of attempts finally got an identifiable shot of it before it disappeared.