The Daily Mail claims that this bonus has been given to 29 senior staff.
If this is true (and I doubt that it applies to so few staff), it has to apply to 29 of the most senior staff in UKBA - people who are on the Senior Civil Service pay bands.
The bottom band of this is Deputy Director, at a starting salary of about £75k (Pay Band 1). The top end of Director General level (Pay band 3) is around £150k.
Whilst in no way defending such payments, as Jake points out, it may not be such a large percentage of salary as some folks imagine.
Many of the problems in UKBA (in delivering) are driven by the Justice system that so favours the individual (or family) that it is very difficult to extract these people and export them. They are given every opportunity to benefit from free legal assistance and every step must be absolutely scrupulously followed and faultless, or they cry foul and get to remain for 'another day'.
By way of example, we then get dim-witted politicians bleating that Failed Asylum Seeker families are locked up for too long - 'not fair on the kids'. Too damn right, but if you don't keep them locked up together, you can't export them together. Anyone would think UKBA enjoy forking out for the cost of detaining them.