What is important about mobile uhf cb antennas?

In the run up to legalisation, some people wanted the old VHF bomber frequency around 220 MHz (unused since WW2) for UK CB. This would have offered much better conditions for CB: nice clear channels without the chronic overseas interference there is on 27 MHz. This interference is often so severe, it even stops local contacts from being made, rendering 27 MHz CB totally useless. However, the vast majority of users were not technically minded enough to realise what a bad slot 27MHz was, and had already purchased American-sourced equipment, so the preferred option for legalisation was the U.S. 27MHz AM system. While technically this was one of the poorest possible choices for a short range person-to-person radio system, and was already allocated for other services, the CB community lobbied vociferously for it. The final legalised service was a compromise - a band at 27MHz was allocated but using FM and offset channel frequencies 27 - 27 which were incompatible with the U.S. system.