Ham Hill Archaeology 2012 reports that –

Ham Hill is the largest prehistoric hillfort in [Britain]. Owing to the generally vast size of hillforts, excavation is often small in scale, leaving us with comparatively little understanding of their use and construction, and the reasons for their appearance in the Iron Age (from around 800 BC). The chance to excavate this nationally significant site has arisen because the Ham Hill Stone Quarry wishes to expand.

Meanwhile, This is Somerset reports that a Facebook group –

…has been set up to protest against the “devastating” effect of quarrying on Ham Hill. Two companies quarry the distinctive Ham stone from the hill with permission from Somerset County Council, which controls quarrying in the county. But a concerned Yeovil resident has accused the council of “turning a blind eye” to damage to the areas caused by digging.

[The resident] …wrote to English Heritage to voice his concerns and posted the body’s reply on the Protect Hamdon Hill Facebook page.
A spokesman for English Heritage said: “We do not believe that there is an alternative material available that meets the very specific needs of conservation projects. “The quarrying is being undertaken with our knowledge and consent and in the context of planning consent from Somerset County Council and Scheduled Monument Consent from the Department for Culture, Media and Sport.” A Somerset County Council spokesman said: “Ham Stone is required for maintenance of many listed buildings both locally and nationally – it is not a common stone and there are no other economically viable places for it to be quarried.
Is the degradation or destruction of one heritage site justified on the grounds that it serves the ‘very specific needs’ of another? Or should we pay special attention to the operative words ‘economically viable’.
See also Kate Shrewsday’s feature here.