Event Relating To A System Thirtieth Anniversary This Month.

[JoanieN]

Can't get started as I can't crack the aforementioned event! Any help appreciated.

[albaqwerty]

name of crossword please.
How many letters and any placed?

[dannyk13]

Casualty 'one shot' episode?
http://metro.co.uk/2017/07/29/casualty-to-broadcast-special-one-take-episode-for-tonights-series-finale-6815443/

[bhg481]

Death of Diana is probably favourite for the event.

[donny48]

Is the wording of what we assume to be the clue correct ?

[albaqwerty]

bhg, that's 20 years, not 30 :-)

[bhg481]

I wondered when someone would spot that.

[JoanieN]

Sorry, posted this incorrectly so that the publication etc not visible and can't seem to amend it! It's The Oldie Genius crossword 351, August 2017. They all need the solution of what I erroneously placed in the 'title'.

[albaqwerty]

I cleaned my specs this morning :-D

[dannyk13]

Joanie, how many letters and do you have any placed?

[donny48]

Each of twenty-eight clues comprises a definition part and a hidden consecutive jumble of the answer’s letters including one extra letter; the extras spell a four-word description of an event relating to a system, the thirtieth anniversary of which occurs this August. Seven clues, without definition parts, consist of cryptic indications of the unchecked letters of their answers; these answers are names of some of the original 2 (unclued) of the system in question.