Britain's oldest bell foundry in London

It is a scene unchanged for generations.

Molten bell metal – a bronze alloy of 22 per cent tin, 78 per cent copper – is poured into a mould at the Whitechapel Bell Foundry in London’s East End.

The foundry – listed by Guinness World Records as the oldest manufacturing firm in Britain – was formed in 1570 in the reign of Elizabeth I.

One of two remaining bell foundries in Britain (the other, in Loughborough, was recently threatened with closure), it made Westminster’s Big Ben and Philadelphia’s Liberty Bell.

White-hot-chapel: Two bells are cast, from a tin and copper mix at a heat of 1,170C, at the Whitechapel foundry

Today, it is in the centre of a large Muslim area and its neighbour is The East London Mosque. Here, we show two replacement bells being cast for the parish church in Weston, Hertfordshire.

The church has a peal of six bells, which are being overhauled at the foundry. The four smallest were in good condition and will return to the belltower after refurbishment and tuning. But the largest bell, cast in 1682, and the second, cast in 1867, were found to be flawed.

They were broken up and melted down in the furnace at Whitechapel at a temperature of 1,170C.

For whom the bell tolls: A workman tuning the bells tests the sound by striking one with a hammer

The molten alloy is transferred from the furnace to this one-and-a-half-ton ladle, hauled across the foundry using a pulley system, and poured into moulds specially designed to match the remaining four originals in style, shape and, most importantly, tone.

In another moment at the foundry, a newly cast bell for another church is being tuned so it perfectly complements its partners.

The workman is striking it with a hammer while holding a high-quality microphone in his left hand. The black box with red lights behind him measures the pitch of the bell to one-hundredth of an oscillation per second – 0.01Hz. Bells are deliberately cast to ring at a pitch a semi-tone higher than their final tone.

This allows metal to be shaved away using a giant lathe – the bell is literally being ‘fine-tuned’.

Ring in the change: Two foundrymen make hand bells while standing next to steel moulds that cast the chimes

The electronic equipment measures not only the main ‘strike’ note of the bell, but five harmonic notes that influence the finished bell’s tone.

These are all affected by the shape and thickness of the bell.

Concentric rings of shiny metal on the bell left by the lathe show whether it has been tuned or not. In the muddle picture the bell's identity is cast into the base – Dennington No5 F#. It is the fifth bell in the peal and sounds an F Sharp.

It will be installed in a church in Dennington, Suffolk. In the last picture, two foundrymen are making hand bells.

In front of them are a row of small steel boxes containing compressed sand moulds for the set of bells.