Cold Water Isolation Valve Tap / Switch Missing

[dans107]

Hi,

We're in the process of moving house and when I've gone to turn off the two isolation valves for the washing machine, the red one's there but the blue one appears to have snapped off (and it's not floating around anywhere...)

Is there any way I can turn it off without turn the water supply off to the whole house? It looks like an allen key might fit in, but don't want to unpack everything to find them if it won't work!

Thanks in advance.