I decided to use 'Polyfilla' to cover the bases as this would be cheaper than 'Bastex' , so I've been applying a layer of it to bases carefully around the figures feet and then letting it dry overnight. I then watered down some suitably sand coloured paint and painted it onto the filler.
When it's dry I then apply some PVA glue in patches and sprinkle with static grass .
The watered down paint pooled in the recesses of the filler and so I've not needed to highlight the bases . This is NOT my favourite task but it's getting done and I will feel virtuous at the end of it !.