A great company for small organised walking groups - used to be max 16 is ATG - Alternative Travel Group in Oxford England. They do walks of varying difficulty with really knowledgable guides, bring you delicious lunches and great quality hotels and dinners. They even move your luggage on day to day. They also organise independant walking tours where they give you maps and information and move your luggage on for you. We have walked from Pisa to Siena in Italy with them - they are great!