OK, but nothing to preclude Mr Williams either----who may have proved more pliable under pressure than Mr Givens (who seems to have insisted he ate a sandwich of the non-chicken-bones variety......)
If the lunch remains were a set up, Givens would be the choice because Williams was supposed to be with Jarman and Norman.
Givens was on his own and already had form with the local authorities, so was easily controlled.
I've come to accept that Jarman and Norman's differing statements are a result of trying to cover for Williams and his lie that he wasn't on the 6th floor. Williams tries everything in his power to distance himself from the SN at lunch-time.
For whatever reason, Williams, Jarman and Norman don't co-ordinate what they are telling the authorities, hence the conflicting accounts.