A number of unm collaterals in this family. A bit of investigating in social media and the GRO suggests the following:
Descended from 4th son of 8th baronet:
Simon Jonathan S-T (born 1948), 2nd m 1978 Marian Janet MacAULEY had issue:
1. Edward John S-T (born 1979) m Helen DRIVER (year uncertain) and has issue:
1.1 (a son) H J S-T (b Q4 2013 Kent)
1.2 (a son, twin, order uncertain) R J S-T (b Q4 2013 Kent)
2. Harry Philip S-T (born 1980) m 2008 Katherine ____ (she has taken his name). They possibly have issue; they are resident in Cardiff, so these are speculative and no m/m/n to corroborate:
2.1 O J E S-T (b Q4 2013 Cardiff)
Possibly a dau, seen in social media, but no obvious candidate in the GRO.