I had to decline the offer. It's unfortunate, but the role I was offered was so far out of my area of expertise it made absolutely no sense career-wise. Disappointed as others DGs (the ones I actually interviewed with) told me they were looking to select me for relevant positions, but were unable to do so I had already been booked (by a DG which didn't even check if I was interested). The traineeship office wouldn't answer emails; she unit itself was helpful and trying to be flexible, but it was too late as the role had already been determined. Such a dysfunctional system.
Anyway, accept/decline deadline is today so I guess some folks on waiting lists will be getting offers soon.