Jack Sugden (actor Clive Hornby) has been in the series from the start

Student Ben Ladlow, from Leeds, was sent the package, containing story plots as well as details about locations and filming schedules.

The 24-year-old sociology student has no connection to the long-running soap.

An Emmerdale spokeswoman said: "We are taking it very seriously and are currently investigating how the mistake has been made."

Healthy ratings

The package included details of plots for several months of episodes, including love triangles, an unexpected pregnancy and a blackmail storyline.

It also reveals where and when the action will be filmed.

Emmerdale, set in the heart of the Yorkshire dales in the north of England, is one of the UK's top soaps.

It started out as quaint daytime rural drama Emmerdale Farm in 1972.

The soap is now one of the ITV1's stalwart shows, with a younger cosmopolitan cast and lifestyle.

Its ratings are also healthy - helped by a move towards dramatic storylines - and regularly attracts nine million viewers.