This isn't really an answer as such, but there's too much to ask to put in a comment. Phonetic spelling of the name isn't much use I'm afraid. You've said its late flowering and vigorous, so its likely a Prune group 3 or viticella group type, but it would be helpful if you could describe the flowers and foliage. For instance, were the flowers very large, or were there lots of small flowers? What colour were the stamens in the centre? Were the flowers double or single? How vigorous was it in terms of height and spread, around 15 feet or 35 feet high? was it deciduous or evergreen?
There are hundreds of varieties of clematis, so this extra information should help to narrow down the field, so please edit your question adding as much information as possible.