@Courtenay: Now I think about it, of course Lewis fostered several young evacuees at his own home near Oxford during the war. I forget whether that happened during the earlier evacuations (1939-1940) or the later ones (1944), though... does anyone here know? If he actually took in evacuees himself in 1944, that might explain him thinking of the war being over a couple of years later for his fictional evacuees in the Narnia books.

Yes, I believe that C.S.Lewis did foster a family of three sisters who were young evacuees. Oxford was particularly safe during WW2, when Hitler hoped to conquer UK & make Oxford the country's capital. Or so I was told by the tour guide when I went there. There was an initial wave of evacuations of children to the English countryside in 1939, before WW2 air raids set in later, during the Battle of Britain. I daresay that these evacuations were ongoing, throughout the War, when children were sent as far away as Canada, though one such ship, loaded with British children, was sunk in the Atlantic. Regional cities like Liverpool, Birmingham, Glasgow, Edinburgh, Manchester, and, most notoriously, Coventry, were also struck by these air raids, not just London or Edinburgh. Did the Doodlebugs target London, in particular, I wonder? Somehow, I doubt it. 

After WW2, not exempting Cambridge, there was a period of austerity, possibly why Lucy & Edmund might not have liked what they got to eat, whilst staying with Eustace Scrubb, in what I took to be the school holidays in that book. 

A quick question: in which evacuation did Lewis host children, 1940/41 or 1944?  Or did he do that throughout the entire war? If it was one or the other, wouldn't it make sense that he'd write about the one that affected him?

About VDT and the "job lecturing in America for sixteen weeks."  While I'd agree that the trip would be both expensive and dangerous during the war, it isn't entirely precluded by the facts.  His lectures could have been hosted as part of a War Bond drive (if that's what they were called in the US - I forget now.)  There were quite a few instances of lecturers from Great Britain going about on fundraising and recruiting tours in the States, Canada, and perhaps other places as well. 

The thing to ask is "What subject was Mr Pevensie lecturing upon, and to what sort of people?"  If it was ordinary subjects, then it was most likely after the war.  We aren't told; I think most of us assume that they would have been school-type subjects.  But were they?  If so, why was he doing the tour in summer?  We aren't told what his regular job was, are we?  Mind you, in those days, you didn't have to be a professor or "expert" in order to be invited to tour and talk, about almost anything under the sun.

If it was during the war, the most likely subject he'd be speaking on would be the war itself.  The war effort, the conditions prevailing in England, the women and children being evacuated, and so forth.  Including appeals to support the war effort with supplies and funds and later, troops.  That type of job would have justified the cost and the risk of travelling, though it doesn't explain Susan going along.

Now as to what Lewis really intended, that's beyond my scope to decide. Just another possibility.

@Aileth: About VDT and the "job lecturing in America for sixteen weeks."  While I'd agree that the trip would be both expensive and dangerous during the war, it isn't entirely precluded by the facts.  His lectures could have been hosted as part of a War Bond drive (if that's what they were called in the US - I forget now.)  There were quite a few instances of lecturers from Great Britain going about on fundraising and recruiting tours in the States, Canada, and perhaps other places as well. 

I once read a book about someone called Dietrich Bonhoeffer, written by Eric Metaxas, who was a Pastor, Theologian and an Anti-Nazi dissident. People like him, & especially some refugees he helped get away from Germany, could & did lecture in America during World War II, & when he was executed, in April,1945 there was a memorial service for him in England, using the English hymn: For all the Saints, who from their labours rest. This makes me think that C.S. Lewis, who, I believe, was connected with such work, himself, when he was on Radio in UK, making programs during the War, like "The Problem of Pain", might have had these sorts of people in mind, when he sent Mr Pevensie and Susan on a VDT sixteen-month lecture circuit. USA did not actually come into WW2 until 7th December, in 1941, and before that, it was essential to warn people of USA of how horrible that regime was, & how their neutrality in WW2 could not be maintained indefinitely. 

Posted by: @aileth

If it was during the war, the most likely subject he'd be speaking on would be the war itself.  The war effort, the conditions prevailing in England, the women and children being evacuated, and so forth.  Including appeals to support the war effort with supplies and funds and later, troops.  That type of job would have justified the cost and the risk of travelling, though it doesn't explain Susan going along.

In the context of the book itself, though (VDT, that is), the story is explicitly set after the war. As I quoted earlier in this thread — and this really blew my mind because of the utter inconsistency with LWW, if that original story is set in 1940 as I always assumed — the first chapter of the book mentions the adventure that the children had at the Professor's house "long ago in the war years". So the war must be over by the time Mr and Mrs Pevensie and Susan go to America. If it was 1942 as the "official" timeline says — and as it would have to be if LWW is set in 1940, because the internal timeline of the books is very clear that one year elapses between LWW and PC and one more year elapses between PC and VDT — then the "war years" most definitely wouldn't have been "long ago". They were still going on and would do so for another three years!!!

So while it's not impossible that Mr Pevensie could have been commissioned to lecture in America during the war years on some topic relevant to the war, that clearly wasn't what was in Lewis's head when he was writing the start of VDT. Again, I can only conclude that Lewis just didn't keep track of exactly what he wrote about the setting of each book, and was even vaguer about it by the time he compiled the timeline that Walter Hooper later published! (As others have mentioned, we don't know the exact circumstances of how that timeline was compiled, and it may have been during the last months of Lewis's life when he was seriously ill and naturally couldn't have spent much time going back over the Narnia books in detail.)

If the trip was just after WWII ended, and considering the parents seemed to be absent from the children's lives during the war, I am going to say they were involved in the war itself. They might have been cryptographers, or working with Britain's version of the CIA during WWII. Or, perhaps Mr. Pevensie was a physicist, involved in nuclear research. That would add a twist! It's likely Lewis didn't go that far, but I like filling in the gaps in the stories.