example.rb

task :postcode_import => :environment do
  puts "\n\n Importing PostCodes"
  lat_long_res = []
  CSV.foreach "lib/data/example.csv" do |row|
    if row[0].include? " "
      postcode = row[0]
    else
      postcode = row[0][0..3] + " " + row[4..-1]
    end
    easting = row[1].to_i
    northing = row[2].to_i
    en_to_ll = Silva::Location.from(:en, :easting => easting, :northing => northing).to(:wgs84)
    lat_long_res << en_to_ll
  end
  lat_long_res.flatten
  lat_long_res.each { |lat, long| Postcode.first_or_create(lat: lat, long: long)}
end

example_postcodes.csv