Good faith duties are still narrowly construed in English law.
The debate about the extent of a good faith duty in English law continues to rumble on and in 2015 the courts continued to construe express good faith obligations narrowly.
In Portsmouth City Council v Ensign Highways Ltd  EWHC 1969 (TCC), a case that considered a general good faith obligation in a long term, Private Finance Initiative (PFI) road maintenance contract, the judge found that the council was not subject to that duty when it came to its contractual obligation to assess the award of service points, which required the exercise of a discretion.
The Judge did find, however, that the council was subject to an implied obligation to make the contract work; namely that it would exercise its discretion by not acting in an arbitrary, irrational or capricious manner and also by acting honestly and on proper grounds.
It seems that the good faith clause was used to import into the implied term two extra, fact-specific duties. Contrary to the approach that was being taken in order to force Ensign to negotiate the original contract, which the council could no longer afford, the council could not simply award the maximum number of points for each contractor default.
(Note this case was heard before the case of Arnold v Britton was decided, the court followed Rainy Sky SA v Kookmin Bank  UKSC 50 by interpreting the contract using commercial common sense.)