Stamp duty when buying out other half of house

Back in 2003, my sister and I bought a house together. We were both first time buyers and did not have to pay stamp duty. I am now buying my sister out - What are the stamp duty implications? Will I have to pay stamp duty on the half I am buying from my sister

Have you read existing threads on this topic? For example this recent one:

Stamp Duty Query -- Buying my friend out

For what it's worth SD on transfers between related parties is charged at half the normal rate due to "consanguinity relief".

thanks Clubman.
it's with solicitor at moment.