Excel table to ArcGIS not plotting correctly

Discussion created by Keljarrett on Apr 22, 2014
Latest reply on Apr 23, 2014 by MKennedy-esristaff
Hoping this is in the right section. I have several shapefiles that I need to pull the attribute tables from, data cleanse in Excel and then load back up to ArcGIS as a single file. I have modified the attribute tables to create a decimal degrees longitude and latitude in British National Grid co ordinate system, same as all my features and maps. If I try and then upload the data back to ArcGIS, by adding the Excel file to the map and using the Display XY Data pop up, the data is drawn miles out on the map and all the data points are clustered together.

I have looked around various forums and can't work out what I'm missing, so any advice would be appreciated.