I have an area in West Sussex, there are no Muntjac on it. However they are nearby, but a major road and railway line seems to have halted their spread; for the time being.
There are also no Muntjac in Kent, I have heard many reports, but I personally have never heard or seen one dead, alive or at the game dealer who I know. Roe are in Kent, but only west Kent. Fallow are fairly widely spread, but there are large areas of Kent without any deer what so ever.
On the subject of munties l am in prime muntie territory here (cambs) hardly a day goes by without seeing one let alone actually going out after them.
It would be interesting to know the extent of their northerly distribution, l have heard of sightings as far as Newcastle but l suspect that these are probably local escapes from private parks if there are actually any that far north because l think the natural migration would not have made it that far yet but maybe l am wrong.
l suspect that there will be a limit to there northerly distribution because as we know they can be susceptible to prolonged cold conditions but who knows what will happen as we seem to be getting milder winters and these little creatures are so adaptable.
I believe the Mammal Society who are the recognised authority in the spread and decline of mammalian species in the UK have them tracked up as far as the Humber on the east coast and the Lune on the west coast.
I have to disagree with you about Muntjac in Kent. They are here in numbers but only down towards Hastings way. I have seen a number around Broadoak Brede when out stalking fallow (did'nt see any fallow though!) and have seen two run over on the A21. None up by me in Tonbridge though.
None in Cornwall, people say they see them but no one has shot one and you never see dead ones on the road, but i did see a dead one on the road yesterday just east of Honiton, so another twenty years they might just make it across the Taymar.
l see muntjac run over around my area almost daily and this is because the little critters are everywhere we have a large population in these parts, so if you are starting to see them on the roads it may mean that the local population is on the increase or maybe just an unfortunate one of prospector, given time they will colonise all southern counties they do not necessarily need woodland they are living in the gardens in my village and surrounding villages using the dyke's and hedgerows for food and shelter as well as the goodies on offer in the gardens, they are also in the middle of Cambridge l was asked to advise them at the local biological gardens in town were they have a population of them.
Good territory is at a premium around here we do not have to much woodland locally, l think the bucks become very tolerant of each other but l have witnessed a mature buck hot on the heels of lesser bucks on more than one occasion l have had them almost run into me completely oblivious to my presence and it is usually the young bucks that tend to get knocked over on the roads.
The rumour that I heard was a munty was picked up dead years ago on the A9 around Dunkeld, but this road kill was supposed to have been brought up from England as a prank!!! As Im aware there a no wild Munties in Scotland!!
I have seen muntjac in East Sussex, not too far from Gatwick, but they are thin on the ground. They were on an estate on which there were also roe, fallow and the very occasional sika and although I never saw all four species on one day, there were several days on which I saw three.
I have not personally seen them but a friend described regularly seeing deer that were probably muntjac pretty close to the Scottish border near Carlisle but they might just have been roe.
Generally if you were to draw a line from the Humber to the Severn, pretty well anywhere south of that line will have some muntjac apart from some of the coastal areas. There are plenty of muntjac to the north of the line but much more thinly spread.
Whilst I am not disagreeing with AndyL about Muntjac being in kent, I will state again that I am not personally aware of Muntjac being actually seen and shot in Kent after 30 years of stalking.
There is one member of this forum who tends to quote a fair bit from the web, which is were he probably does most of his stalking, therefore I will in this instance follow suit. Please refer to http://www.jmcc.gov.uk/pdf/pub07_tmp_leaflet.pdf TMP UK MAMMAL'S update 2007, which shows that they are on the border of Kent, but as yet not recorded in Kent. However they are on the border of west Kent, which is the only natural way they can come into kent, as we have the sea to the south, east and most of the north except for London and the Thames, bit of a barrier I woudl say.
Hastings by the way is in East Sussex, not Kent, at least it was the last time I looked!
I have heard reports of Muntjac in Kent for a number of years, even as far east as Canterbury. I have good friends who are keepers in the area, and although they have reported small slots in some wooded areas, no one has seen or shot a Muntie. I have also spoken to local people over the years who claim to have seen them, yet not one has been brought in shot to anyone I know. I for one would be very happy to see them in Kent, as it is not the hot spot of the UK for deer.
As for Muntjac being in the Scottish highlands, I have my doubts, but you never can tell, someone may have introduced them, as a member of this forum has already stated "stranger things can happen" much like it would be strange not to have the regular TROLL on this forum "stranger things can happen"