Sensors using tilted fibre Bragg gratings (TFBG) are now widely used and intensively developed due to their high precision, interference immunity, small size and low price. One of the parameters that can be measured with them is the angle of light polarisation plane rotation (LPPR) propagating in the optical fibre. Existing TFBG sensors are based on measuring the power of light at a selected wavelength, which results in a limited measurement range and low precision. Other methods are based on advanced algorithms that process a selected range of the TFBG spectrum using a wavelet (DWT) or Fast Fourier Transform (FFT). However, achieving high precision over the entire measurement range is impossible due to the similar FFT and DWT coefficient variation. In the present study, it was identified that a cascaded connection of two TFBGs, rotated relative to each other, allows for obtaining the variability function of the cladding mode minima (MMCl) shifted in relation to one another as a function of the LPPR angle. This enables direct utilisation of the minima values in the algorithm calculating the LPRR angle based on the light spectrum. Furthermore, the obtained MMCl functions exhibit a significantly lower level of interference than the previously employed FFT coefficient variability waveforms. These phenomena were used to develop a method for calculating the measurement result from the measured light spectra. Based on the cladding mode minima values measured for angles 0°, 2°, 4°,…, 180°, a calibration was conducted. An algorithm was developed to select the MMCl functions that will be used to calculate the measured rotation angle. The developed solution allows measuring the light polarisation plane rotation angle with equal precision in the range of 0°-180°. Applying the proposed method has improved the measurement's stability. Compared to existing solutions, MAE was improved by 2.6% and MSE by 66%.