davejb
http://www.airsceneuk.org.uk/oldstuf.../falklands.htm
British Aerospace's (BAe) Manchester Division received instructions to design and fit probes to the Nimrod fleet on 14 April (1982 )and Marshall Aerospace of Cambridge received similar instructions in respect of the Hercules the next day.
The probes were taken from RAF stocks, being mostly removed from de-commissioned Vulcans, plus some new ones intended for the VC10 tankers that were then under construction. The Nimrod probing programme exemplifies the collapsing of development schedules,
BAe Woodford taking just a fortnight to complete the initial installation, thereby enabling the first 'wet' prod to be made on 30 April. The second aircraft with machine-produced parts was rolled out only two days later and service clearance for the kit was obtained on 5 May. An initial batch of sixteen aircraft was modified and designated Nimrod MR Mk2P (for probe). To compensate for the effect of the probe on its handling characteristics a small ventral fin was added beneath the tail along with small finlets that are often mistaken for radio aerials above and below the tailplanes.