If you notice that your local servers when in GMT are 1 hour behind when in BST then you probably have an incorrectly configured iLO card, to check this login to the iLO4 like this:
Navigate to the Network and iLO Dedicated network port:
Click on SNTP:
Ensure you have the correct timezone, for the UK it should Europe/London not GMT/GMT - if its GMT in summertime your clock will be -1 hour.