In reply to captainfire576:
Seconding is generally easier than leading. It's partially psychological, but also a question of route finding, risk assessment, gear placement, carrying a rack, rope drag and the weight of double ropes etc.
I climbed Technical Master, a boulder problem at Millstone this spring, which gets UK Tech 6b. But also this spring I failed to climb an HVS 5a on Stanage. So it looks like we might be in exactly the same boat, and I would think virtually everyone is in a similar, if not identical, predicament.
In sport climbing top roping a route might be between half and a full letter grade easier, and seconding about half a letter grade. But in trad the difference between leading and seconding is going to be massive, lets say on average 3 whole grades. In other words, I would expect HVS leaders to be able to second up to E3. However, on really serious routes, the difference becomes much, much greater.
You mention UK Tech 6b. That could be anything between E3 and E9. What E grade are we talking here?
If it turns out that you got up every single VS you tried and most HVS and were able to second up to E3 then I am not sure you really have the problem you think you have.
If you were very tall (and therefore heavy) I would also expect you to have difficulty with climbing 5a routes, but be able to lank the occasional far reach which might get 6b but seem nothing more than 5b to you. And again the world would be in order.
Perhaps we would need to know a little more about you?