I've been provided with a dataset containing some coordinates, but I don't recognise the coordinate system used. They look like standard UTM coordinates but the values don't match up with what I expect, which are locations in Scotland, UK.
For example, a random record gives
GIS_X as 349275.0 and
GIS_Y as 636198.0. Using these coordinates along with zone 30, plugging these values into http://www.rcn.montana.edu/Resources/Converter.aspx results in WGS coordinates not far from the equator, which is evidently wrong.
The datasource is checked daily for various errors so I'm fairly certain the data provided to me is correct; any ideas for how these values might make sense, given the expected result?