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Context. Period variations have been detected in a number of eclipsing closecompact binary subdwarf B stars (sdBs) and these have often been interpreted ascaused by circumbinary massive planets or brown dwarfs. Various evolutionaryscenarios have been proposed for these stars, but a definite mechanism remainsto be established. Equally puzzling is the formation of these putativecircumbinary objects which must have formed either from the remaining postcommon envelope circumbinary disk or survived its evolution. Aims. In thispaper we review the eclipse time variations (ETVs) exhibited by seven suchsystems and explore if there is conclusive evidence that the ETVs observed overthe last two decades can reliably predict the presence of circumbinary bodies.Methods. We report 246 new observations of the seven sdB systems made between2013 September and 2017 July using a worldwide network of telescopes. Wecombined our new data with previously published measurements to analyse theETVs of these systems. Results. Our data shows that period variations cannot bemodelled simply on the basis of circumbinary objects. This implies that morecomplex processes may be taking place in these systems. From eclipse timevariations, it has historically been suggested that five of the seven binarysystems reported herein had circumbinary objects. Based on our recentobservations and analysis only three systems remain serious contenders. We findagreement with other observers that at least a decade of observations isrequired to establish reliable ephemeris. With longer observational baselinesit is quite conceivable that the data will support the circumbinary objecthypothesis of these binary systems. Also we generally agree with otherobservers that larger values of (O-C) residuals are found with secondarycompanions of spectral type M5/6 or earlier as a result of an Applegate typemechanism

The quest for stable circumbinary companions to post-common envelope sdB eclipsing binaries Does the observational evidence support their existence?