If you follow the news you may be aware that Britain is in the midst of what '60s researchers called a "flap", ie a wave of sightings, genuine or presumed, of UFOs.
We've had sightings in Shropshire, South Wales and Worcestershire.
Of course we are flooded with "rational" explanations, for example the celebrated wedding lanterns, while a handful of serious researchers are calling for more serious research.
UFOs were declared dead and buried by mainstream press and skeptics alike but I am glad they are making a comeback. They serve as a sobering reminder that mankind has a LONG way to go to knowledge and that, as Newton himself said, we should always question our theories, no matter how sound as they appear to be.
As I've already related in previous posts anything flying in the sky is a UFO until it is identified. Of course a few sightings are frauds, hallucinations or known objects (yesterday I was "buzzed" by a brand new C130J military transport plane: you won't believe how much quieter it is when compared to older models) but there's always that small percentage (if 25-30% can be called small) of unsolvable cases.
And that's what we are here for.

A case is only unsolved because there is insufficient information available to determine a cause. It does not imply any particular cause, such as extra-terrestrial craft, for instance.

While I tend to agree with you (you probably know by now that I am no big fan of the extraterrestrial hypothesis) we tend to overlook the fact that we may lack the knowledge to explain some cases or the means to investigate others.
Take the Hessdalen Lights for example: if they had appeared in the '50s instead that in the '90s we would have had the theoretical basis to explain them but we would have absolutely no mean to investigate them. Spectrometers back then were heavy, fragile, incredibly expensive and impossible to use outside controlled lab settings.
Or take meteors for example. We know exactly what they are, how they behave and can even predict a "shower" with precision. Yet until recently when people (including me...) talked about hearing booms and hissing sounds associated with meteors they were said to be either hallucinating or mistaken. Yet the most recent studies seem to support the fact that there are odd sounds associated with meteors, though the dynamics are still unknown. But we'll get there with time and effort.

Humph. I notice that none of this has made the BBC World News.

What are the answers/ explanations being bandied about?

This is all quite intrigueing - please keep us posted as appropriate. I did a search on the BBC new site and found nothing...

I guess that going on National television and explaining a UFO sightings in terms of highly-advanced yet sound physics (see some theories about small, local and temporary "distortions" of the space-time fabric) is considered more suicidal than saying that the Daleks are here.

I think the subject of UFO's is in reality too complicated for the mainstream media to fully digest and regurgitate to the masses. Much easier to find "experts" who will either completely debunk or claim the Martians have landed! The same goes for paranormal research in general, in my opinion.

Of course, much of their wok relied on a fairly literal interpretation of witness statements. With advances in neuroscience we now know that witnesses are more suggestible and their experiences and memories more 'flexible' than used to be the case. Seeing may still be believing but it is not necessarily an accurate account of the objective world.

I have sat in ghost vigils, for instance, being told there are ghostly voices whispering when I knew for a fact it was noisy plumbing. I have sat in the dark watching small lights apparently moving (even though they were stationary) while knowing full well it was only autokinesis.

I am not saying we should reject the theories of ufologists rather that it is time for a thorough re-examination of witness testimony, in the light of new discoveries in neuroscience. Before we speculate about space-time distortions, we need to know if a witness really saw what they think they saw.

It's curious to note that all three these persons obtained a PhD in Astrophysics, hence they were most likely to be influenced by advanced physics. All three were involved at one point or another in a space program: Hynek developed tracking models for satellites as part of Professor Whipple's equipe, Vallee worked on the supercomputers used in the Apollo program and Poher worked at the CNES (the French equivalent of NASA) in Tolouse in their sounding rockets program. They may be weird (as physicists tend to be in real life, I assure you) but they do not speak at random.
Poher and his GEPAN equipe developed a set method for the French Gendarmerie to collect samples and interrogate witnesses in UFO cases. Gendarmes are instructed never to mock anyone reporting a UFO, to use the set interrogation method and forward the results to GEPAN: see thisofficial communication. Similar material has been distributed to Aero-Club and astronomical societies.
If your French is up to the task feast your eyes on this, a true treasure for the serious investigator!

There are bigger problems than interview techniques. Almost all UFO cases all are 'one offs' and many involve single witnesses. As such, you may be relying entirely on the recall of one person for almost all the information about many incidents.

In experiments involving staged incidents, few witnesses produce an accurate account of what they've seen, often inventing some details while missing many others. And that's with incidents witnessed just minutes before. If there are multiple witnesses, accuracy increases somewhat by comparing individual witness statements. However, that is no help with single witness sightings.

Most UFO reports are caused by natural events. The few unexplained ones may only be so because there is insufficient information. I, for one, would not see that as a satisfactory basis on which to speculate about the true nature of UFOs.