Hi Jacqueline,
at 7kg,this now makes me believe that it is hollow,but being hollow does not diminish its value..this type of casting is the norm...and at £40...you got yourself a really good bargain...either way....it has a nice patina,...when you take it along to your local auctioneers,may i suggest you go here
Caldervalley Auctioneers..they specialize in Antiques & fine Art...you can find them here
Fairlea Mill
Ellenholme Road, Luddenden Foot, Halifax
01422 886 648
good luck