Good Morning Joanne, 
 
Thanks for your question. 
 
We don't have a direct comparison with that model but I would say that the closest matches we have are either our Origins Pocket Latex 1500 or our Hybrid 5. 
 
The Origins Pocket Latex 1500 is a pocket sprung mattress with an in-built latex top layer. This mattress has a firm feel in the comfort layers whilst also providing support from the springs. To make it mimic the Pegasus mattress a bit closer you could also look at adding a Coolblue Topper. Whilst the Origins Pocket Latex 1500 has that in-built latex layer making it a no-turn mattress, by introducing the Coolblue Topper you're increasing the lifespan of the mattress because the topper is fully turnable. Please see the information here on our correct care and maintenance tips. 
 
Similarly our Hybrid 5 is a full foam mattress with again that completely detachable Coolblue Topper. Hybrid Foams are great for pressure relief and give a progressive similar sort of sink in sensation to memory foam but without the heat issues associated. 
 
Similar to the Origins Pocket Latex 1500, the core foam mattress on the Hybrid 5 is non-turnable but the Topper can be turned allowing you to increase the lifespan of it. 
 
Please see below for the breakdown of the layers in both the mattresses we've discussed here;
 

 
 
I hope this has answered your questions fully but if you do have any further queries please don't hesitate to contact us on 0161 437 4419. Our office opening times are Monday to Friday 8am to 8pm and Saturday and Sunday 10am to 4pm.
 
Kind Regards, Lee.