Thank you Sacha and David that looks very similar. The blooms in my
photos are not fully open so I will have another look at them tomorrow.

It is interesting that they are called hedgehog broom because not
knowing what the plant was I gave it the nickname "blue broom". In my
photos they look a bit more purple than in reality. To the naked eye
they are more blue than purple and very attractive.

They seem to be thriving at the moment even though we have had plenty
of rain this winter and early spring (the end of the drought in
Portugal maybe). They all seem to be in very well drained locations
though on fairly steep banks.