Proj4js.defs["EPSG:27700"] = "+title=British National Grid\
  +proj=tmerc \
  +lat_0=49 +lon_0=-2 \
  +k=0.9996012717 \
  +x_0=400000 +y_0=-100000 \
  +ellps=airy +datum=OSGB36 +units=m +no_defs";