Harry is meeting Elena at the Russian ballet, not at a ball. The meaning of their meeting would change. Harry must be trying to find out who is impersonating him and why Elena is suggesting that Harry is still asking her to spy on her husband.

the press release for Episode 2 mentions "ballet". I suppose that Ruth would attend the official reception after the ballet as a translator. I am still remembering the lovely 3.5 scene in which Ruth was watching "Red Shoes". She looked so sweet and innocent. Times have changed.

How does Sasha know that his mother is a former Western spy? Is it because he is a double Russian/British agent? or did she confide in him? Did Harry tell him?

Monday 26 September
9.00-10.00pm BBC ONE and BBC ONE HD
 http://www.bbc.co.uk/spooks
Calum is attacked in the street during a routine intelligence sharing exercise with MI6, as the spy drama continues. His laptop is stolen containing highly classified information on MI5's undercover assets. The names are soon leaked, putting the assets' lives in danger, and it's a race against time to stop the next spy being exposed.
Tariq scours London's CCTV network, but the muggers are highly trained and have used sophisticated cleaning routes to ensure they remain undetected.
Meanwhile, Harry meets Elena at the ballet but the Russian FSB are on her trail and Elena's own son, Sasha, is forced to take deadly action to prevent his mother being revealed as a former Western spy.
Section D discovers who is leaking the assets' identities, only to realise that this is part of a bigger plan to discredit MI5. Tariq makes a breakthrough linking the muggers to a surprising third-party but can he get to Thames House in time?
Calum Reed is played by Geoffery Streatfeild, Tariq Masood by Shazad Latif, Harry Pearce by Peter Firth, Elena Gavrik by Alice Krige and Sasha Gavrik by Tom Weston-Jones
PPR

I'm clinging on to that phrase as well Everyone know no one gets to even touch Harry... unless it's Ruth, the thought of Elena and Harry getting closer during S10 makes me feel a bit ill

The Writers have to know what an uproar that would be if anything ever came close to happening between Harry and Elena
Then again maybe the writers want to torture us and see how long we can hold out
A jealous Ruth would be an interesting thing to see, if Harry and Elena get close and Ruth was aware of their 'personal history'... it depends how deep Harry and Elena's history goes... I mean, it could turn out he didn't actually have any kind of affair with her during that operation after all, that it was just work, but getting someone to spy on their husband, there had to be some thing that made her decide to do it (Like Adam and Ana in S6)

My mistake, I meant Ballet... which could be a black tie event in Episode 2 and not 1, I can't see their being a black tie event of Ep1 at all with everything else thats going on (Harry's inquiry, introducing new characters, Max Witts death being solved ect)
If it's what we saw in the trailer (Which might not be for Episode 1, its just a teaser and judging from the fact there are clips with Harry in a Tux and in a suit having a gun against him makes me think its not just an ep 1 trailer)
then it can't be some kind of secret meeting between Harry and Elena because we know Ilya is there. (We saw someone trying to attack him and Harry stopped the oncoming attack) then again it might not be the same episode as the one in the 8 second trailer.
So perhaps she wants to find out just what exactly is going on, but with enough cover from people around her to protect her from the FSB who are trying to track her down.
If they are trying to get to her does this mean Ilya knows that she once spied on him, would he not have questions as to why the FSB are looking for his wife and how much exactly does Sasha know about it? Why does he know and how does he know his mother his spied on her own side?

Is the idea of someone impersonating Harry part of a bigger story arc over the whole Series or is it more for the Ep1 storyline... or is it the actual running storyline for S10? It seems like too much of a complex thing for it to just fit into 1 episode

I like the idea of Ruth being there as a translator will she be dressed up as well though, undercover perhaps?

I am very worried about the remarks "the uncompromising toughness of Spooks" and "an ending that is faithful to the spirit of the show, the characters, and reflects the ten years of great drama". In the back of my mind I have always feared that both Harry and Ruth might be sacrificed for the principle of great drama. It will make me very angry if Kudos will give us their so predictable trademark ending. I hope that Kudos will be audacious in a positive way.

I am concerned about the writers' response to the question if "they kept anything from the Grid set as a souvenir when filming was completed?" I cannot help wondering about their reply "The only thing we managed to swipe was a small piece of fake glass from the final episode." Does it mean that there is an explosion or somebody is shot on the Grid. I am thinking of the glass walls in Harry's office. To me this sentence is a huge spoiler and not in a good way.

I'm also worried about that H/R comment, if its a traditional Spooks ending that could mean potential death for someone... not a nice way really to end 10 years of a great drama, but we shall have to wait and see...
About the glass, by "Set" it could mean a set, doesnt mean it has to be the Grid... unless they threw a party after filming and broke the glass of Harry's office

Also if you now look on the BBC site there is a new pic for 10.1... Harry in a tux, so now I'm forced to go back and change my mind that the Ballet in ep2 is not the black tie event, I dont think it is at least... again we'll have to wait and see.
I just really hope that if Elena drives a wedge (Even if accidentaly) between Harry and Ruth it doesn't mean they lost faith in each other, Elena's character is beginning to worry me already and we've not even seen her onscreen yet