From Northern Scot
.....by the additional growth in 2007-08, referring to it as 'just a little less than three per cent of the total programme cost'. The majority of the overspend has come about during the flight trials process, which has highlighted the need for modifications. There are problems with the pitch of the aircraft – something which the MoD says is not unusual – and that has accounted for about half the cost growth.
Its not really clear from this reporting which overspend is being referred to - the massive one from a few years back or the more recent 07-08 increases. It sounds like they are actually being criticised for the recent increases (i.e. ontop of the previous £700m ones) which are it seems more modest in scale. If this is true the flight trials increases would be half of the 3% increase, or 1.5% of the total.
EDIT - just read in an earlier post that the recent overspend is an additional £100m, hence £50m for the additional 'flight test' related problem - whatever that is/was.
Finding problems late on in development programmes is always the most expensive time to find them.
Continuing my chalk and cheese comparison series of posts, another real world example to consider is the Mercedes A Class. Costing $1.5Bn to develop, the fact that they discovered it had a safety flaw (it rolled over during an Elk swerving test) after already having delivered nearly 3000 cars to customers cost them $250m to put right. This effectively represents a 16% increase in the initial development cost - ouch!