Anybody know the Servowarm Elite HE boiler?

Servowarm tend to rebadge other makes, very possibly a Baxi or Potterton.

Now secondary heat exchanger can mean one of two things: Either it's the water-water heat exchanger on a combi. Or it's a second primary heat exchanger fitted downstream (from the flue gas point of view) usually in an attempt to uprate a boiler design to be a condensing type. Hence the HE standing for High Efficiency?

Well, I'm no expert, but it ain't a combi and can't think its intended as an uprate as its already of the condensing variety.

So if it has a secondary heat exchanger it must be a second primary unit. This feature is common on (poor) uprated designs where a stop gap attempt is made to redesign the boiler as a condensing unit.

It might be somthing like a a rebadged Pott. Suprima HE. To the best of my knowledge Servowarm don't 'make' boilers.