It had occurred that something with smaller holes might help - currently have a big drencher rose installed.
But the bath suffers the same problem as the shower (they're both connected to the Grohe Rapido T).
I was testing the kitchen tap and the bathroom basin last night and they do both...
The basin flows a little better but is that linked to smaller pipe? The basin will also suffer from loss of hot, but not as readily as shower, again I assume linked to size of pipe.
I have recently had a new thermostatic shower/bath mixer (Grohe rapido T), fitted, which is fed by a Vaillant ecomax boiler (c. 6 or 7 years old).
The problem is that the pressure is terrible and the mixer cannot sustain hot water for any length of time.
Now i understand that combi boilers...