The UK 73kHz band was made available in June 1996. A Notice of Variation to an individual's licence was required before using the band - I understand more than 50 were issued, though only 30-odd were ever used. There is no precise date of the start of the band; it was simply announced in the June RadCom that applications for NoVs were invited.
Although a few test transmissions were made earlier, the first ever two-way contact was made on 14 Feb 1997 between myself and Peter Dodd, G3LDO over a distance of a few hundred metres.
The frequency limits were 71.6 to 74.4kHz, about the bandwidth of a single SSB transmission, and for much of the life of the band, we had to contend with an extremely strong commercial RTTY (and later two-channel data) transmission from Rugby.
The band came about as a stop-gap, being offered to UK amateurs whilst a Europe-wide allocation was being considered (eventually to become the 136kHz band). 73kHz was originally to be available for three years, but a case was made to extend this twice to allow experiments to continue.
These experiments proved that, even with extremely inefficient antennas leading to ERPs of a few milliwatts, distances of hundreds or even thousands of kilometres could be covered using the right techniques.
The final close was at midnight UTC on 30 June 2003, and Peter and
I made the band's last QSO.
I am the only person to have operated on 73kHz from Wales. Details.