It's from Dr. Johnson, as quoted in Boswell's life:

Patriotism having become one of our topicks, Johnson suddenly
uttered, in a strong determined tone, an apophthegm, at which many
will start: 'Patriotism is the last refuge of a scoundrel.' But
let it be considered, that he did not mean a real and generous love
of our country, but that pretended patriotism which so many, in all
ages and countries, have made a cloak for self-interest.



http://www.concordance.com/cgi-bin/letsr.pl
Bingley

Bingley