Testing the relevance of rapidly deepening cyclones near the British Isles for the identified 
shortening of the RP over Western Europe. Results by Pinto et al. [2009] suggest that a significant 
part of the storm frequency change (i.e., frequency above the 95% quantile) signal in the western European 
area may be due to changes in rapidly deepening cyclones near the British Isles, named "British Bombs" 
(their section 5.4, labelled BB hereafter). For example, their Table 9 and Figure 19 give an indication of 
the enhanced number of extreme systems over this area (A1B only). In order to verify this we have further 
analysed the subsample of 20C and A1B with BB cyclones removed. The RP changes presented in Figure S5 are 
almost identical to the results presented in Figures 2c and 2d) respectively, i.e., removal of the BBs does 
not remove the climate change signal in Box 3 VOR (Figure C b). However, the quality of the GPD fit seems 
to be degraded. The magnitude of the VOR RP changes are slightly lower but still significantly different 
from 20C for RPs greater than 1 year (not shown). With BB removed there also still remains a significant 
difference in the annual CP RP of storms in Box 3 (Figure S5a). Hence, these new results demonstrate that 
changes in rapidly developing cyclones in the vicinity of the British Isles are only a partial contribution 
to the detectable change in frequency and intensity of storms over Western Europe.

