London-based?
Then howcome their admin is in Edinburgh, and all the support staff I talk to on the phone are in Edinburgh.
We're a customer of Lumison, and on the whole I really like them. They generally get things right, and if you have a problem you can very quickly get hold of someone who not only understands your problem, but can also fix it very fast. On the downside, twice in the last year they've managed to have a serious core routing outage, including one just last Wednesday (caused by some absent-minded soul forgetting to commit switch config changes to NVRAM).
Hopefully this expansion will give us more of the good service and less of the careless failures...