It was then (when/that) the police arrived.

[Tan Elaine]

It was then (when/that) the police arrived.

Which word in bold should I use or should neither be used?

Thanks.

[5jj]

I'd use 'that'.

[BobK]

I'd use 'that'.

Me too, in that context. But 'It was then - when the police arrived - that I ran away.'


b

[BobK]

I'd use 'that'.

Me too, in that context. But 'It was then - when the police arrived - that I ran away.'


b

[Kotfor]

Does it mean that "it was then that" is a set phrase? Seems like "when" doesn't really spoil the meaning but still it's not exactly this set phrase.

[Chicken Sandwich]

NOT A TEACHER

It was then when/that the police arrived.
It was here where/that we met.

I think that 'It was then when...." is acceptable to some speakers, as this example demonstrates:

It was then when I noticed that it was not me who suffered strong changes but him.
[...]
It was then when I really began to worry.
(The Portrait - Julio J. Orvananos Archer, see here)

Other speakers my argue that "then when" is tautologous. See this thread. Perhaps 5jj (or someone else of course) can tell us whether or not the two sentences I quoted above have a similar structure. I think it's a similar case, but I'm not entirely sure.

[5jj]

It was then when I noticed that it was not me who suffered strong changes but him.
[...]
It was then when I really began to worry.

[...] Perhaps 5jj (or someone else of course) can tell us whether or not the two sentences I quoted above have a similar structure.

Personal, non-expert opinion: they seem to be the same to me. I would use 'that' in both, but I have no strong objection to 'when' these days.