How to reference a .NET FW4 WCF Service from VS2008

We have a web service, created using .NET framework 4 in VS2010 which works absolutely fine with a .NET 4 client. However, if a VS2008 (.net 2,3 or 3.5) client tries to create a reference to the service all we get is errors:

Metadata contains a reference that cannot be resolved: 'http://xxx.xxx.xxx.xxx/WSApprentice/Apprentice.svc?wsdl'.

Metadata contains a ref开发者_StackOverflowerence that cannot be resolved: 'http://xxx.xxx.xxx.xxx/WSApprentice/Apprentice.svc?wsdl'.

The WSDL document contains links that could not be resolved.

There was an error downloading 'http://xxx.xxx.xxx.xxx/WSApprentice/Apprentice.svc?xsd=xsd0'.

The operation has timed out

Metadata contains a reference that cannot be resolved: 'http://xxx.xxx.xxx.xxx/WSApprentice/Apprentice.svc'.

The remote server returned an unexpected response: (400) Bad Request.

The remote server returned an error: (400) Bad Request.

If the service is defined in the current solution, try building the solution and adding the service reference again.

We have tried creating the reference using both the standard Add Service Reference and also using the Advanced option Add Web Reference. This also fails.

Can anyone provide any hints or tips on how to resolve this one please?

Thanks,

Rob.