When Olna were designed by Hawthorn Leslie we had to incorporate two very special requirements. Firstly the ships had to be able to carry out a RAS in nuclear fall-out conditions. All cargo valves and winches had hydraulic remote control systems. We had no idea how much pipework would be involved, so we just bought 5 miles of pipe per ship. It was insufficient.
The second inovation was that the ships had bridge control for the steam turbines. Until the Olna class, the fleet replenishment ship plodded along in at steady pace and the Carrier came alongside and matched the oiler's speed. In the Olnas the procedure was reversed and the RFA Captain was provided with a bridge lever to match the carrier's speed.
The MoD decided that the only way this system would work would be to eliminate all back-up controls to prevent them working against each other. My memory is failing as to which ship was involved, but when either Olna or Olynthus were on full load trials and proceeding at full astern, the single manoeuvering valve spindle fractured. The only way the ship could be stopped was to close down the boilers. At full displacement however the ship could not re-enter the Tyne and the pumps were steam driven.
Most of you old salts will know that it is not possible to achieve long term directional control of a conventional ship going astern. The ship begins to turn in a ragged circle and spiral upwind. This is what happened and thankfully she set off in circles towards Norway, pumping tanks, chased by George V and other members of the Tyne tug fleet. An attempt was made to land a replacement spindle by helicopter, but the RAF pilot decided that he did not want to make his first deck landing on ship without a heli-deck crew that was going astern in circles!