One of my all time favourite products that I use on a regular basis is Rusk Sensories Bright Shampoo.
What they claim: Rusk Sensories Bright Shampoo is an effective cleansing shampoo that instantly revitalises & brightens dull, lifeless, silver/grey or white hair with translucent brighteners.At first I was sceptical this would work, who wouldn't be a little scared to put bright purple shampoo on their hair? Saying this I read many reviews about silver and purple shampoos fixing the dreaded brassiness that blonde hair tends to get so I gave this a try.
It's brilliant and a total must for blondies! It costs around a tenner for quite a big bottle (400ml) but you only need to use it once a week or when you feel your hair needs a bit of a boost.