Whilst you specified a 5 minute walk on your criteria I think you should also consider the fact that there is generally very good public transport in London where prices would be cheaper a bit further out. The location is close to several rail stations (Blackfriars, Farringdon), the new Crossrail route (farringdon) opening in a few weeks and tube lines (central, circle, district). With the new cross-rail route it should be possible to access zone 4 locations in 20 minutes.
Whilst you specified a 5 minute walk on your criteria I think you should also consider the fact that there is generally very good public transport in London where prices would be cheaper a bit further out. The location is close to several rail stations (Blackfriars, Farringdon), the new Crossrail route (farringdon) opening in a few weeks and tube lines (central, circle, district). With the new cross-rail route it should be possible to access zone 4 locations in 20 minutes.