he wants her around so he can covertly partake of her supply of Gowland's. ;)

I don't really know. Perhaps his attentions to her are a manipulation to keep Mr. Shepherd in line?

I can not believe that he would seriously be in danger of falling into romantic blindness for Mrs. Clay due to his obsession with rank and titles. Lady Dalrymple on the other hand...Sir Walter seemed excessively attentive towards her.