Table: budshead
Columns: name
labour
conservative
political_party
electorate
constituency

Question: What is the smallest electorate for the Conservative party in South West Devon constituency, with over 2 conservatives and a name of Plymstock Radford?
SQL: SELECT MIN("electorate") FROM budshead WHERE "political_party" = 'conservative' AND "constituency" = 'south west devon' AND "conservative" > 2 AND "name" = 'plymstock radford'