I found this in my local Home Bargains but it could be national. Root Perfect Spray 75ml in four colours Blonde,Light Brown, Med Brown and Black.
Root Perfect Instant Root Concealer 75ml Spray in Medium Brown covers root regrowth and any greys in seconds, for an all-day flawless finish. Its precision spray and quick-drying mist easily blends to give a natural look, extending the time needed between hair colouring. Both quick to use and easy to wash out, it's perfect for when you're on the go.