I have heard sometimes the [æ] vowel in either concil [kaʊnsl/kounsəl] or counsellor [kaʊnsələ(r)/kouns(ə)lər], as in this British pronunciation of counsellor. It sounds rather like cat [kæt] than cow [kau], but I'm not sure if it's really [æ]+[u]. Am I hearing wrong?
In your link, the [a] from the British /aʊ/ is certainly much longer than the American one, and perhaps a little bit more front, but not to the point that I would classify it as [æ].
If you are interested in hearing what that diphthong would sound like with a true [æ] nucleus, it is supposedly realized as [æɔ] in Australian English (here is one source on that, and here is an archive of recordings of a text from different English dialects, including Australian).
A similar pronunciation also occurs in certain regions of the USA. For instance (according to Labov, cited in this Wikipedia article) /aʊ/ is fronted to [æʊ] in Midland American English.