Reply to my email...

Many thanks for letting us know about this. Damage usually starts with the school summer holidays but it seems the fine weather has brought out the vandals a term earlier this year. One of my jobs is to visit all the Guardianship (English Heritage) long barrows in the county four times a year and this has certainly occurred since my last visit. I can't tell from the photo whether this is just stones from the nearby drystone walls that have been thrown in or damage to the structure of the chamber. I doubt they are from the roof of the chamber as those are set in finest Ministry of Works concrete but I'll get out there later today to see what has happened and let you know the result.
Regards
Toby Catchpole
Senior Project Officer
Archaeology Service
Gloucestershire County Council
Shire Hall
Gloucester
GL1 2TH

Tel: (01452) 425681
Fax: (01452) 425356
www.gloucestershire.gov.uk/archaeology

I will let you know the result of Toby's visit when he updates me.
Probably a useul contact to keep for future reference.