Tactics
Like many secret technologies, RAFTER's use was attended by the fear of over-use, alerting the quarry and causing a shift in tactics which would neutralize the technology. As a technical means of intelligence, it was also not well supported by the more traditional factions in MI5. Its part in the successes and failures of MI5 at the time is not entirely known.
In his book Spycatcher, MI5 officer Peter Wright related one incident in which a mobile RAFTER unit in a van, or panel truck, was driven around the backstreets in an attempt to locate a receiver. What with interference and the effects of large metal objects in the surroundings, such as lamp posts, this proved futile. Later, however, they concluded that the receiver itself had been mobile, and may at one point have been parked next to the van, hidden by a high fence.
Read more about this topic: Operation RAFTER