Just looked at the longest running corrie character ken has been over taken by Dennis and Emily

just looked at no they have not dennis tanner only being there 5 years but in the list they counted when first apperence to there last which in dennis case is 53 years but he not been there all that time so ken is number one Emily only been in the show for 47 yearsd ken been there for 53

Dennis and Ken have both being in Corrie since the very first episode, However Ken has being on the show constantly since the start and Dennis had a break of about 40 years before returning. If I remember correctly I think Emily came in it the following year.

Yeah I think you're right. Dennis and Ken appeared in the first ever episode in december 1960 and Emily first appeared in the eighth ever episode which aired in January 1961 so even though she appeared in a different year, in reality she has only been in it a few weeks less than Ken (not taking into account any breaks the actress has had etc)