I believe that this answers many of the questions.
Click the image to see it clearly in full size. See the complete poster
at this link.
The unqualified statement “no more than the cost of a call to an 01 or 02 number” is intended to mean what it says.
The comments at
http://www.nhsglos.nhs.uk/telephonenumbering/ offer explicit reassurance, confirming that
for all 03 numbers this does apply to inclusive packages and calls from mobiles.
The reason for choosing the 0300 range is given, although there is no explicit explanation of why the 0345 range was not chosen.
Whilst the latter portions of the numbers are being retained in most cases, there is some re-jigging of the middle portion to reflect organisational changes as a result of the NHS reforms, so that each (new) organisation may have a distinct block of numbers, as was the case previously.
For an organisation with many 084 numbers, 034 only provides a temporary "cheap fix". A move to 030 (or 033) has to happen when new numbers are required. I still maintain that this provides an appropriate option for DWP and HMRC, as in these times of restricted expenditure cheap fixes are needed.
One is always looking for ways in which a job such as this could have been done better. I have to say that if the excessive time it has taken for this change to be made has been used to get it right, then it has been well spent.