UK Car Repair: car fails to start, vauxall, linkage

Question
QUESTION:  why does my vauxall senator automatic fail to start after been driven for 5or 6 miles.

ANSWER: You have to give me more details, When does it start, when did this problem begin? Does it stop by itsself etc.

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QUESTION: starts first time on a morning,when i drive to the shops.park up,get back in and when i try to start it it will not start.but if i juggle the gear stick for 5 mins,the car will start.why is this?is there a sensor on the gear box ? that tells system that the car is not in neutral but it actually is!

Answer
You mean it does not turn over, the starter is not operating! Not starting is a description of when the engine turns but does not start.  Yes, there is a switch on the gear linkage which prevents it starting in gear. It is most likely loose or out of adjustment. I'm not exactly sure of where it is but if you go to a parts source they will have a catalogue which will show the location.