If it was a rocket ship it was travelling rather slower than might have been expected, but at 24 metres long and 5.6 metres high it was unmissable.

Covering the 14 miles from Sharpness Docks to its landing site just off the B4088 Bath Road at Haresfield at a little under five miles an hour the chrome beomoth was never going to break any speed limits.

In fact it didn't even arrive under its own steam, travelling instead on the back of a truck owned by specialist haulage firm Allelys of Studley, bought in to handle the 40-tonne corrugated cylinder.

Jon Brookes, assistant transport manager at Allelys, explained just what people had witnessed and why they were called in to drop off the mystery package.

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"It is not big for us, but it was still quite an operation. We had to get BT and Western Power to lift some of the lines along the A38 to move it safely. We were still three hours early," said Mr Brookes, who added that the firm was equally at home moving 320-tonne cable reels for the oil and gas industry.

So what was the mystery object?

It will become a cooling tower for the controversial Javelin Park incinerator being built just down the road from Wyevale Garden Centre and unmissable if you are travelling down the nearby M5 past Junction 12.

When operational it will burn around 190,000 tonnes a year for steam-powered turbines to produce electricity.