31. And what proprietary claim was Mr Cobbe making that an estoppel was necessary to protect? 32. Alternatively, there was an equitable estoppel . 33. A fourth category, equitable easements arising by virtue of proprietary estoppel , is contested. 34. It is one type of file-wrapper estoppel , the other being prosecution history estoppel. 35. It is one type of file-wrapper estoppel, the other being prosecution history estoppel . 36. Estoppel allows an implied promise to act as a shield against litigation but never a sword.37. There are a huge array of different types of estoppel which can arise under English law. 38. Estoppel is an equitable ( as opposed to common law ) construct and is therefore discretionary.39. Further, there was no existing relationship between the parties that could give rise to estoppel . 40. Second, an easement may also come about through an express assurance, triggering proprietary estoppel .
