I used to really like the pre- refurb LGW CH. It was small, cosy, with fantastic attentive service , but granted, it didn't have the wow /bling factor of the LHR CH.
My last visit there in October was pretty poor, but for that matter, the 3 visits I've had since then to the LHR CH haven't been brilliant either.
Slow service seems to be a common problem in both these days , however the concierge at LHR is still top notch and ever helpful

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DL