Is the seller obliged to sell once contracts are exchanged?

[thussain]

My question relates to the period between exchange of contracts and before completion.
I understand that if the buyer pulls out he loses his deposit. Is the seller allowed to pull out? If so, what are the consequences?
Thanks
btw - this is a hypothetical question as I am assisting in the purchase of a property NOT trying to get out of a contract myself.

[buildersmate]

It is possible but likely to be very costly.
The buyer may try and sue you to get you to leave the property.
You will lose about 10% of the selling price plus the legal costs incurred.
If there is a chain of people involved in this which now collapses, those people might also try and sue you.