Thinking about it, it is probably the Mail trying to avoid writing the word "anus".
He must be in IW - surely.....or are we back to the dark days of 2013 and The Year of No Projects? The alternatives:
(1) James Ivory's ongoing fantasy casting of Richard II (the fan fiction version)
(2) Will TH be in the new Same Mendes production at the Royal Court (casting still not announced).
My guess is neither. My other guess is that TH might be filming for Infinity Wars but how big a part it ends up being could depend on how Thor 3 does with preview audiences. In other words: he might be filming scenes, but not have been announced just in case Marvel bins him. Marvel seems to have a difficult relationship with Loki. He is a hugely popular character but they had to be told to put more of him into Thor 2 (and imagine how bad that movie would have been with even less Loki).