My New Oxford American Dictionary states:

ilk |ilk|
noun [in sing. ]
a type of people or things similar to those already referred to : the veiled suggestions that reporters of his ilk seem to be so good at | fascists, racists, and others of that ilk.

• ( of that ilk) Scottish, chiefly archaic of the place or estate of the same name : Sir Iain Moncreiffe of that Ilk.

ORIGIN Old English ilca [same,] of Germanic origin; related to alike .

USAGE In modern use, ilk is used in phrases such as : of his ilk, of that ilk , to mean ‘type’ or ‘sort.’ The use arose out of a misunderstanding of the earlier, Scottish use in the phrase of that ilk, where it means ‘of the same name or place.’ For this reason, some traditionalists regard the modern use as incorrect. It is, however, the only common current use and is now part of standard English.
Regards,
Rex.