We have been working on improving the way to access UK census data and have provided 2011 UK census data as a series of dynamic map services allowing users to change symbology, view pop-ups and carry out analysis using the data in the ArcGIS Online Platform.

A recent upgrade to the ArcGIS Online Basemaps added support for re-sampling at scales larger than the map has data for (ie when zoomed in beyond the dats). This allows the client application to re-sample the closest available scale and display that, instead of a 'Map data not available' image.