UPDATE: The Royal Navy have confirmed that no naval exercises were undertaken last night anywhere off the Cornish coast.

Earlier reports had suggested the strange noise might have been caused by naval gunfire. 

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UPDATE: The British Geographical Survery says its automated reporting system was not activated by any significant earth tremors yesterday evening.

The last movement recorded was on May 13 at Lostwithiel, measuring 1.8 on the richter scale.

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Do you have any idea what the mysterious booming and rumbling noise was that echoed across Cornwall last night?

The series of rumbles could be heard as far as Helford Passage to the west and all the way to St Austell just before 9pm.

A reporter for the Packet happened to be at Helford Passage last evening and described it as coming from the east, with a series of low percussive booming sounds. He likened it to the bass notes from a music festival drifting over the hills.

Was it a quarry blast? Something hitting the atmosphere?

Police have no information and no-one called them to report it.

Did you hear the rumble? Do you have any ideas what it might have been?

Let us know, in the comments box below! (Or contact us through all the regular channels by clicking here)