What a cracking day for mid March! I won't do a blow by blow account here (instead you can get a feel for it from my vid - search YouTube for "Merthyr Magic timpent") however the interesting bit was towards the end of the flight, past Ross-on-Wye, where there was definitely convergence caused by the sea air coming up the Severn Estuary (see 4:25 and 4:44). I was trying to get under the convergence front running to the left of the screen at 4:54, but I didn't connect with it. The wind was pretty much due S at this point, whereas it had been between SW-WSW earlier.
I've heard people talking about connecting to the SBF (sea breeze front) and riding it north, and it certainly looks doable, but as it was I ended up just on a long cross-wind lifty glide all the way to the deck just short of Tewkesbury.
Interestingly, Tosh, who was not far behind me, headed on a more northerly route towards the Malvern hills, but he didn't manage to connect with anything either and landed near Malvern.