isochrones to its 0.3–1.2$M_{\odot}$ stars as they descend their PMS tracks (Naylor et al. 2002), or $35\pm 3$Myr determined from the re-appearance of lithium in the atmospheres of even lower mass stars (Jeffries & Oliveira 2005). It is old enough that inner circumstellar discs have dispersed – no accretion-related H$\alpha$ emission or $L$-band near infrared excesses are seen from its solar-type members (e.g. Jeffries, Totten & James 2000; Young et al. 2004). However, cluster members with $M<1.4\,M_{\odot}$ are still in the PMS phase, stars with $M<0.4\,M_{\odot}$ are fully convective (Siess, Dufour & Forestini 2000; D’Antona & Mazzitelli 1997) and it is significantly younger than other well-studied open clusters like IC2391 ($50\pm 5$Myr) and the Alpha Per cluster ($90\pm10$Myr).

NGC 2547 was observed at X-ray wavelengths by the [*ROSAT*]{} High Resolution Imager (HRI). Jeffries & Tolley (1998) found a rich population of low mass, X-ray active cluster candidates with $10^{29}<L_{\rm x}<10^{31}$ergs$^{-1}$. Puzzlingly, the solar-type stars of NGC 2547 seemed slightly [*less*]{} X-ray active than their counterparts in older clusters. Their activity peaked at $L_{\rm
x}/L_{\rm bol}=10^{-3.3}$, whereas the most active stars at lower masses had $L_{\rm x}/L_{\rm bol}=10^{-3}$ as expected. Jeffries, Totten & James (2000) ruled out anomalously slow rotation rates 