issues with kitchen hot tap only - its not the tap!?

Hey Dudes,

My Hot water tap in the kitchen had p*ss poor pressure which started recently. Through advice from my dad and a local plumber i have changed the taps in the kitchen which has increased the flow from a drip to a dribble. The hot taps upstairs work fine. The tanks are full, the cold is good throughout. This is a recent problem just on the downstairs kitchen hot tap.

Any ideas please gentlemen would be greatfully received i'm scratching my head,

I look forward to hearing from you,

Chops