An underground cage that collapsed leading to the deaths of four men could have been safely built by an 'experienced contractor', an inquest heard.

The man who designed the reinforcing cage, part of a high pressure test bay at Claxton Engineering in Great Yarmouth, suggested three 'safe' working methods.

They included fitting supporting Z-bars early in the build, pouring some concrete after completing the lower section and using a crane - though the latter was not 'economically viable'.

Structural engineer Richard Carr, who worked for Scott Wilson Group, added it was not standard practice in the industry to suggest working methods to contractors.

And he told the hearing at Sprowston Manor, near Norwich, that designs were still at a preliminary stage - and clearly marked as such - when contractors started work.

Daniel Hazelton, 30, and Adam Taylor, 28, both of Rickinghall, and Thomas Hazelton, 26, and Peter Johnson, 42, both of Stanton, near Bury St Edmunds, died on January 21, 2011.

The third day of a jury inquest, today, heard that the men were fitting around 18 tonnes of steel bars to the top of the cage when it collapsed.

Mr Carr said 'temporary works' may have been necessary to ensure stability during the build.

But Julia Kendrick, for principal contractor Encompass, said this may not have been 'obvious' to people who were not structural engineers.

John Elvin, for the Health and Safety Executive (HSE), said photos of the structure suggested the men's work did not show any 'variation from the drawing' and there was no suggestion of improper working methods.

The inquest continues tomorrow.