Waitrose, with about 200 stores, is one of John Lewis' brands
Department store group John Lewis has said this summer's "staycation" trend and the poor weather had worked in its favour after sales rose 5.6% last week.
The chain saw growth at all but eight of its stores with the figures coming after revenues increased by 6.3% in the previous week.
The boost was put down to increased footfall due to the poor weather and good responses to new ranges.
John Lewis's Southampton store saw the strongest gain with a rise of 15.9%.
Across the chain, the home department led the way with a sales rise of 10.5% against last year, followed by fashion at 8.2%.
Electricals and home technology was down 1.9% amid discounting by rival stores.
As well as strong trading at its 27-strong department store business, the retail bellwether said online sales jumped by 22.8%.
At grocery business Waitrose, which is also part of the John Lewis Partnership, sales remained strong after a 9.5% rise in the week.
In March, the group said its profits declined last year amid "deteriorating conditions".
The partnership said its underlying profits fell 26% to £279.6m, while sales rose 3% to £6.97bn.