Electromagnetic microphones with oil or grease damping put an end to most difficulties, the first example being made up from a loud speaker damped with turbine oil. This enabled the research station staff to put on an 'outside broadcast' early in 1923 from the Oxford Street Picture House, Manchester. Several miles of buried cable were used, despite expert opinion that the frequency band that could be transmitted would be too narrow to give reasonable reproduction, and not long afterwards this became the general method of transmitting outside broadcasts.

On the receiving side of broadcasting an experimental laboratory was set up and many types of receivers designed, from the 'crystal and cat's whisker' upwards. In the autumn of 1922 an advertising campaign presented the Cosmos crystal type Radiophone at £4 10s, and valve type Radiophones soon followed. The starting of a radio section of the M-V Club betokened growing interest. In 1923 the enthusiastic amateur was offered Radiobrix, a series of numbered units mounted in standard cubes, such as an h.f. amplifier or an l.f. amplifier; with these he could build his own receiver, from a crystal set to a six-valve model.

In 1924 development work in the research department under E. Y. Robinson produced the Cosmos Shortpath valve. This marked a radical change in construction since the clearances between electrodes were only a fraction of those previously employed. In spite of the improvement in performance (and the excellent scientific reasons for it), the new 'trade' was sceptical of the commercial prospects, but eventually Shortpath valves were made in large numbers, thus laying the foundations of the modern valve industry.

OVERSEAS TRADE
The christening of M-V in September 1919 was accompanied by the birth of the Metropolitan-Vickers Electrical Export Company, which was formed to handle overseas trade, always an invaluable support to the business. Towards the end of the war a study had been made of world trading conditions and markets by representatives on the spot, and the end of American control had opened up fresh fields for expansion.

The new company was launched with Hilton as chairman, H. J. Lloyd as managing director, E. J. Summerhill as administrative (later general) manager, and F. S. Holder as representative at Trafford Park. McKinstry was brought back from Australia, where he had just been appointed a State Electricity Commissioner for Victoria, and was later associated with Lloyd as joint managing director; on Lloyd's resignation in 1922 his place was taken by C. S. Richards, home from Japan.

Continuing the policy of direct representation wherever the market warranted, the Export Company began with offices in Brussels, Bombay, Calcutta, Johannesburg, Melbourne and