The change seems to be bringing it into line with other "free" museums.
eg: Science & Technology Museum in Manchester is also "free" admission but charges for car parking .... difference there of course is that free parking would be impractical as shoppers etc would flood in.
£2.00 for under three hours & £3.00 for over two hours isn't bad.
Is it a bit cheeky that while blue badge holders are not excused the parking fee coaches are?