Rocker Cover Too Hot

[RonK]

My 2009 Fiesta has developed a problem after I discovered the oil filler cap dislodged from the rocker cover. I drove about 30 miles before I noticed a puff of white smoke coming from the bonnet. The oil filler cap had come off and some oil had sprayed on to the exhaust manifold, causing  it to burn. There was a small flame at the rear of the rocker cover. Luckily it was small and I blew it out before anything caught fire. There was some oil lost but not much - the dipstick showed full.

The engine was then degreased and pressure cleaned. The car then ran as normal after the small amount of residual oil on the exhaust manifold burned off. However after a run of 20 or 30 miles the engine feels hot on my face after I lifted the bonnet to check. There are no warning lights and the level of both the coolant and oil levels are normal. There are no signs of leaks or smoke. However the rear of the rocker cover (near the exhaust manifold) cover feels very hot to touch. In contrast, the front facing part of the rocker cover feels just warm. There is also an intermittent burning smell in the passenger compartment.

Can anyone advise on what could be the problem? A displaced heat shield? Cylinder head problem? Dodgy water pump? Thanks in advance of any advice.