By the late-war period, the same developers had produced a model using a cavity magnetron known as the Microwave Zone Position Indicator (MZPI).

This was not a concern during the war because the information would be handed off to nearby gun-laying radars, which could determine the altitude by scanning up and down once provided with an angle to look at.

The echo of a target would be received by two of these feeds at any given time, and by comparing the relative signal strengths, the elevation angle could be determined to well under a degree.

At the same time, research began on the design of a new high-power 25 cm wavelength (L-band) cavity magnetron, a new large-format long-persistence plan-position indicator display tube, and a data link system to send the information to as many as sixteen remote sites.

By mid-1948 the basic design was complete; it would operate in the X-band at 10 cm wavelength and use ten feedhorns, each one with a 3 degree vertical beam.

[4] In 1949 the Ministry of Supply took over direct control of the TRE and RRDE, and assigned the 3D work the Rainbow Code "Orange Yeoman".

They asked the War Office and Admiralty to consider whether a single radar would be useful for both fighter control and gun direction; fighter control demanded long range which suggested a slower scanning rate than what would be ideal for a GL radar whose primary concern is rapid notifications in changes of location.

AAA would remain in use through a transition period, and there was a desire to accurately feed the information from Orange Yeoman to their existing Mark VII radars.

[6] As the development of the antenna system appeared to be progressing well, in 1950 it was decided to add another feed horn while decreasing the beam width to 2.5 degrees.

This led to experiments with slip-rings that fed the intermediate frequency (IF) instead, with the magnetron transmitters and first stages of the superheterodyne receivers on the rotating platform.

[7] In June 1951, with these problems ongoing, it was decided to move ahead with all the parts that did work in order to get a production system as soon as possible.

This led to a system using a single 2 MW magnetron instead of three ganged ones, feeding them via IF slip-rings, and using separate transmit and receive antennas.

Metropolitan-Vickers (Metrovick) was contracted to build a test system, which consisted of a gantry framework with two turntables at different altitudes, the lower one with the transmitter antenna and the receiver above it.

This would provide track while scan capability that would greatly ease the task of deciding which AA guns should be trained on which targets.

[8] Near the end of 1949, the RRDE staff were shown the ongoing work on the Comprehensive Display System being developed for the Navy by Elliott Brothers.

A complete system was built at the RRDE with help from Metrovick and British Thomson-Houston during 1951, which was able to track up to 12 targets and had two large-format displays for the direction officers.

[9] At first, the system required the operators to update the information for a given track by watching the radar display and moving a cursor dot with a joystick.

A second group injected height measurements into the storage system at a slower pace, as changes in altitude were much less frequent, so only two or three operators were required for this task.

[10] By early 1953, development was largely complete and the system was given the official name Radar, Anti-Aircraft, Number 4, Mark VIII, or AA No.

In June 1953, the first of these sites was selected, on the hills near Newton[11] overlooking the Frodsham Anti-Aircraft Operations Room covering the Liverpool area and relatively close to the Metrovick works.

[11] In 1953 the RAF took over responsibility for anti-aircraft missiles, with the ultimate goal of removing large-calibre AAA from UK service at some time in the future.

As part of this handover, Orange Yeoman became a TRE project and was assigned the name AMES Type 82, although the actual development remained at the normally Army-related RRDE.

[13] The RAF initially saw a role for the Orange Yeoman similar to that of the Army, and continued development of two prototypes and three production sites.

[17] At closer ranges, the signal began to be picked up in the antenna's side lobes, eventually causing the entire screen to be filled with noise.

[18] The Central Flying School expressed their interest in the Data Handling System as a way to simplify their fighter interception duties.

They abandoned the idea of general anti-aircraft operations and began to focus entirely on the defence of the deterrent force in the form of the V bomber fleet.

[21] Within a few months of the Type 82's being stood down, the Vice-Chief of the Air Staff completed a study on "Conversion of the Tactical Control Centres at Watton, North Luffenham and Lindholme to an ATC role".

[22] Little change was required for the switch to the ATC role, but the chance was taken to convert the antennas to circular polarization, which RRE experiments had demonstrated reduced the clutter from rain and hail.

This was a hexagonal array of metal tubes acting as a lens that separated the reflected signal into a series of vertically stacked stripes, 2.5 degrees wide.

[25] The Type 82 was designed to measure bearing, range and elevation with enough accuracy to place a target return within a 1,500 foot (460 m) box.