That would be with Lloyds then.
You get 4% if (and only if) you have between £4000 and £5000 in the account. You get no additional interest for balances above £5000.
Santander 123 gives 3% for balances up to £20000 which is better overall.
However, if you have more than £20000 then good luck in finding somewhere sensible to put it. A quick look shows that the best I can find is 1.45% with RCI Bank (who?!). Better than 1.05% but not dramatically so.