The mystery bidder circling Welcome Break, the struggling UK motorway services provider, is understood to be a joint venture between SISU Capital, a little-known distressed equities and bond investor, and Swayfields, a private company which operates rival motorway services brand Extra.

The two firms are believed to have teamed up in a bid to thwart a controversial £381.5m (€560m)debt refinancing proposal for Welcome Break tabled by Investcorp, an investment group whose clients are mainly in the Arabian Gulf.