Strong regenerated gratings (~18dB, L = 5cm) that can withstand temperatures in excess of 1200°C have been produced. These gratings have a number of potential applications from monitoring furnace temperatures in various fields, to high intensity optical field-resistant gratings for high peak power fibre lasers. Below the regeneration threshold, stabilisation of type I gratings offers a realistic prospect of balancing grating strength with practical temperature operation up to 700°C. Remarkably, single exponential relaxation, consistent with annealing of a regular rather than an amorphous structure, is observed during isochronal annealing of thermally stabilised type I gratings. Retaining the complex functionality available to type I gratings has also been demonstrated. In particular, complex regenerated gratings (L = 0.5cm) were produced. Two dual channel filter designs ­ a superposed grating and a Moiré grating ­ were fabricated with more than 4% transmission. The regenerated superposed structure showed signs of a small chirp possibly arising from the slightly Gaussian profile of the micro heater hot zone employed. This suggests that regenerated gratings can be thermally post-tailored during regeneration from the seed grating on a macro scale. In contrast, despite the significantly reduced strength and the reduced average index change (measured as a shift to shorter wavelengths) the regenerated Moiré grating exactly preserved the interference profile within the central transmission notch of the grating spectrum, and therefore the embedded phase information of the seed grating.