Trim the beans and cook for 3 minutes in boiling, salted water. Drain and cool under cold, running water. Dry on kitchen paper.
Put each wrap on a clean work surface and paste the far edge with butter. Cover the front half with smoked salmon then spread a line of cream cheese across the front of the wrap and lay cooked beans along, piling them about 3–4 high. Roll up tightly, trim the ends as and wrap in cling film. Chill for at least 1 hour. Slice into 6–8 pieces and serve ends up.