High Altitude Traffic.

I live in Morley, which is midway between Leeds and Wakefield in West Yorkshire.On clear days like it is today i can see a lot of high altitude aircraft,from the trails i can see that they are heavy jets 747 etc etc.As most of them are travelling east to west or vice versa i assume that they must have taken off from other countries (they are at or around cruising height,some lower than others,but none below @20000 ft.
Can anyone enlighten me as to where they are likely to be coming or going to.Sometimes there can be upwards of ten aircraft in view.I would also like to listen to them on a scanner,anyone advise me please.Thanks. Howard .

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