I think so as well but the feathers are a bit rough! Faint supercillium etc but I don't have a good wagtail book (too tedious for my taste) like immature gulls etc but when you do get one its nice to know for sure.
According to the excellent and indispensable BOU "The Birds of Nigeria" by Ellwood et al (2nd Ed) M. f. flava "is widespread and predominant, thunbergi, iberiae, cinereocapilla, feldegg and superciliaris, more local and less numerous. Claims for other races, notably flavissima, are not substantiated.
the racial distribution pattern is complex. About 40,000 have been ringed in Nigeria and recoveries are numerous in N. Africa from Morocco to Libya and in Europe from France to Turkey north to Finland and Russia. Birds ringed in Bulgaria, Denmark, Finland, Poland, Italy, Sweden and Russia have been recovered in Nigeria."
Therefore, by % it is worth looking closely at M. f. flava as well.
Unfortunately I don't have Vol 4 of Birds of Africa - anyone got one for sale?