St. Lawrence Church, Lavernock, south Wales, Marconi and the birth of radio

Situated close to the south Wales coastline betwixt Penarth and Barry is the attractive limestone St. Lawrence Church at Lavernock – small church with an interesting link to radio history.

Attached to the church perimeter wall is a bronze plaque erected by the Cardiff Rotary Club in 1948 to mark 50th anniversary of the first wireless signal being transmitted across open water.

On 13 May, 1897, Italian born Guglielmo Marconi (ably assisted by  Cardiff Post Office engineer George Kemp) transmitted the first wireless signal across open water from nearby Lavernock Point to Flat Holm, a distance of 6 kilometres.

Transmitted in Morse code the first ever messages read:

‘Are you ready?’
Followed by, ‘Can you hear me?’
The reply received was, ‘Yes, loud and clear’.

The morse recording slip for the first message is now on display in the National Museum of Wales.

[George Kemp (left) and Marconi]

Kemp recorded how the experiments progressed:

“Mr Marconi’s apparatus was set up on the cliff at Lavernock Point, which is about twenty yards above sea-level. Here we erected a pole, 30 yards (27 m) high, on the top of which was a cylindrical cap of zinc, 2 yards (1.8 m) long and 1-yard (0.91 m) diameter.

Connected with this cap was an insulated copper wire leading to one side of the detector, the other side of which was connected to a wire led down the cliff and dipping into the sea. At Flat Holm Mr Preece’s apparatus was arranged, the Ruhmkorff coil also giving 20-inch (510 mm) sparks from an eight-cell battery.

On the 10th May experiments on Mr Preece’s electro-magnetic transmission method were repeated, and with perfect success.

The next few days were eventful ones in the history of Mr Marconi. On the 11th and 12th his experiments were unsatisfactory — worse still, they were failures — and the fate of his new system trembled in the balance.

An inspiration saved it. On the 13th May the apparatus was carried down to the beach at the foot of the cliff, and connected by another 20 yards (18 m) of wire to the pole above, thus making an aerial height of 50 yards (46 m) in all. Result, The instruments which for two days failed to record anything intelligible, now rang out the signals clear and unmistakable, and all by the addition of a few yards of wire!”

The church – which appears to date back to 1769 – now only opens on rare special occasions.

[1879 Map via old-maps]

Here’s some more views:

Note the boat around the back of the church, and the wicker structure.

Read more: Marconi’s Welsh wireless revolution [BBC]

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