This, the third essay on the attempt to find the site of Boudica's last battle, improves on previous techniques. A terrain model of the southern UK was searched, by use of a template matching algorithm, to find all the topographic depressions of width approximately 500 to 2000 m and depth 15 m or greater (other attributes were applied) that matched Tacitus' description of the battle-site. After some initial editing of the original sites (2700) to remove those with selection errors and the most obvious of faults, the candidate battle-site list was reduced to 862. These were then subjected to a weighting and ranking process via the application of ten attributes. A crucial step was to examine the choice of routes available to the Roman commander, Suetonius Paulinus, as he considered withdrawal from London after Boudica's destruction of Colchester and the rout of the 9th Legion. The pros and cons for each route are described, discussed and the results compared. The findings were: that Suetonius did not march north-east towards Boudica; that the London to Lewes road to the southern coast would not have been chosen as all the prospective battle-sites are less than one day's march from London; that taking Watling Street to the Kent ports would have been a strategic and tactical error; that marching further north than St. Albans along Watling Street could have led to conflict with flanking and rearward attacking rebel forces; that turning west at St. Albans to follow Akeman Street was a superior choice but one limited to prospective battle-sites (3, 5, 7, 8, 10, 11 etc.) in the Bulbourne river valley, south-east of Tring, if the absence of burning and destruction at Alchester Roman fortress is correct; that the other southern route from London via Stane Street was strategically sound, and that tactically the prospective battle-sites at Dorking (1 and 2) were outstanding; and finally, that taking the Portway directly west out of London was strategically the most suitable of routes and one Suetonius would probably have viewed most favourably. A simple combination of the ranked sites and the most likely choice of route from London would logically indicate that the actual battle took place in the west at Ogbourne St. George (4), Donhead St. Andrew (6), or Shalbourne (9). However, in acknowledging that not all events, dispositions, circumstances etc. were known, it was concluded that the next investigative phase will be best served by examining not only the western Portway locations but also those along Stane Street at Dorking, and the higher ranking sites within the Bulbourne river valley along Akeman Street.