The 32-strong squad, including Warriors Academy product Mullan, have been stayed at Browns Sport and Leisure Complex on the Algarve to prepare for the RBS 6 Nations and had their final training session this morning before returning to England.
The squad stayed at the training complex last year and prior to their RWC 2007 campaign and have enjoyed some quality training and preparation time together before the start of the tournament.
"We are building a good squad," said Johnson. "We are starting to add a bit of depth to our group, more than ever before. There is competition throughout and that is what you need. This is the best squad we have had in my time being in charge and it will only get stronger."