It has certainly turned into a bit of a mystery among those involved.
Of course, the pitch process is designed to give clients a good idea of what an agency is like, but it seems unlikely that an advertiser needs to know information such as how effective the agencies' staffs' deodorant is, how they look with sweat dripping down their faces, or how many ad industry types you can fit into a phone box.
But what other explanation can there be for the size of the room that the supermarket chain's finance division chose for the pitch?
The company saw six agencies in total that day, in a meeting room no bigger than eight foot by ten foot - the atmosphere in the room by the end of all those highly charged pitches must have been musty, to say the least.
Perhaps these finance types have a sense of humour after all and this was a tongue-in-cheek ingenuity test. Or it could be that, given the pitch is a fast-turnaround project with a short deadline, the marketing team simply had not been able to find a larger meeting room for the whole day.
In any other building that could have been a credible explanation. But not when you remember that Sainsbury's has moved into the colossal former Mirror building that looms over Holborn.