Two thoughts
1) Aircraft POH (with UK supplement) and the ANO are your definitive references
2) Any placarding is either there a) from when it was first built or b) due to a present limitation that has come from either the manufacturer or from the CAA via an AWN (Airworthiness Notice). It's probably worth having a word with the maintenance organisation and, if it's the former, then it should be removed. (The fact that it hasn't means they may not be doing their job properly - as that's part of it).