On 8 Jul, 20:17, Hobbyist wrote:
1] Travel from East Croydon to St. Pancras by Thameslink train.

2] Travel from E. Croydon to Victoria by tain, then from Victoria tube
station to Kings Cross tube.

No, you can only use Oyster PAYG on these routes (ie almost none of
South London):
http://www.nationalrail.co.uk/times_...OysterPAYG.pdf

I suspect you were let in at St Pancras International, but Oyster PAYG
is only valid on that route as far as London Bridge or Elephant &
Castle.

If you had a weekly or longer season ticket loaded onto your Oyster
card, then you can use it on any train in the ticket's zones.

U

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