So how would I translate the following sentence into British:
Star Trek has had six series.
It’s a fairly unusual circumstance, but you could say that there have been 6 different TV versions of Star Trek (if that’s what you meant).
I think partly because of the popularity of US TV DVD boxsets, the term season in the American sense now has plenty of currency here. Season and series are both used but I would guess that the American term is slowly supplanting the other term.
Depending on when the book was written, ie if it was in the last couple of years I think this would be as people above have said, a sports bag. Because plastic bags are no longer free, 22c a go nowadays, people pack their groceries into all sorts of bags. I usually bring a rucksack for grocery shopping. PS Dublin isn’t British 
I think series can be used both in the meaning of different years of a single run, and different runs of a single overall show. So you could both talk about the second series of The Next Generation, and about The Next Generation being the series before Deep Space Nine.
Season (in the American sense) is certainly understood, and sometimes used, but I don’t know whether it’s supplanting the use of series. Season already has another meaning in terms of British TV, where it’s the whole schedule of programmes on a channel, for one quarter of the year.
Here is a question for non Brits - do you know what an “allotment” is?
I doubt I’d know what an allotment is if I weren’t an old Eastenders addict.
It’s a patch of land where people without yards can garden, right? I don’t know how the system works (I’m guessing there’s some kind of fee involved), but I’ve occasionally seen references to allotment gardens in fiction.
I doubt this is well known in the US, though. If I hadn’t read about them before I think my guess would have been that an allotment was a kind of pension.
That is correct. The land is usually owned by the local council and is rented out at a very nominal sum (about £25 a year) to the individual plot user.
If I said “donkeys years”, would you know what I meant?
I use that phrase fairly often over here and nobody has ever given me a “huh?” look.
This is another one I’ve encountered only in fiction. It means “many years” or “a long time”. I don’t know why it means that, but it does. 
I wouldn’t expect many other Americans to be familiar with this expression, but in books at least it’s usually clear enough from context. If someone says “I haven’t seen one of those in donkey’s years!” then there’s not much else it could mean.
I hear “in donkeys (or is that donkey’s) years” or in “in dunkeys years” all the time.
Sorry I’m late - I was dilly-dallying!
I wanted to add that real men (and Monty Python sketches set 'op North) wear string vests.
With matching handkerchieffor the ultimate in sartorial elegance.
What. The. Hell.
Surely, he was dressing ironically? Please?
Possibly, OTOH.
That particular individual might have been. Or he might not. The knotted handkerchief was definitely relatively common beachwearat one time.
It’s typical of a certain period where people from urban centres would go to the coast for a holiday.
It was too hot for the usual cloth flat cap, but something was needed to keep the sun off the head… so the knotted hankie made a handy alternative.
You don’t see it so much now though.