'Upgrading' to skinny tyres pointless for London commuting

There is an interesting article in the current CTC magazine about this: Super light race bike vs. Clunky old steel framed wide tired commuter.
The conclusion was that there was no difference in time no matter which bike was used.

...which is fine for a certain type of riding.

But... there aren't any studies to support the long accepted belief that lighter wheels are faster (than heavy wheels) although it's clear that lighter wheels will help you climb, hold a wheel and stay with a group.