Expressflight, I posted facts taken from SEN's own website, which either reflect or are taken from the UK-AIP.
An electrified railway line runs along the eastern boundary of the airport immediately beyond the ILS Localiser array
For larger aircraft types note that taxiways are narrow (15m).
The runway may potentially be considered “narrow” for use by certain larger Code C aircraft (e.g. A319 etc.,) – check with the aircraft flight manual as necessary.
I could have added that another complicatng factor at SEN is the gen avn traffic in the circuit when Easyjet perform overhead arrivals when the SSR is u/s (as has happened recently and NOTAM'd accordingly). However personal observation instead of recounting fact would have attracted invective from the usual quarters so I witheld that comment and purely posted facts.
Aborted take-offs resulting in runway overrun, landing long and fast with subsequent runway overrun and runway execursion on both take-off and landing are not uncommon. Operators at SEN will have looked at the dangers (railway, dual carriageway and church) and planned accordingly or as I posted previously:
I'm sure all users of SEN have appropriate briefings for their flight crew to take account of, and mitigate the inherent dangers