UK properties owned and rented out by by foreign landlords and taxation rises sharply

planetpropertyblog.co.uk/2013/12/16/the-number-of-foreign-landlords-with-uk-property-passes-two-million-mark/

I am confused. Anyone explain?
If a landlord is overseas or "foreign based", why is tax on rent being paid to the UK tax office? Or is tax being paid to the UK tax authorities AND the foreign based landlord's own tax authority in the country they are based in? In other words, taxed twice? And still worth doing?

I don't have any property rented out in the UK, but as a Briton in Poland would I pay tax to the UK tax office or the Poland tax office on a UK property I was renting out if I ever become the landlord of a property in the UK?

Because tax needs to be paid on the rental income if a property is rented out in the UK, regardless of if the landlord is abroad.

The Non Resident Landlords Scheme taxes the UK rental income of non resident UK landlords.
Basically, UK based letting agents deduct basic rate tax ( 20% ), from rent collected on behalf of non resident landlords. If there is no letting agent appointed by the landlord and the rent exceeds £100 pw, the tenant has to deduct the tax. This is then paid to HMRC.

hmrc.gov.uk/cnr/nr_landlords.htm?iframe=true&width=80%&height=80%

Its the same way in Poland.Rental properties in Poland are taxed in Poland irrelevant of the owner if he is a foreigner or native.But some countries like US require to declare that income in there returns with proof of tax(pit forms) and is although not taxed again.