Yeah, let's have a look at yer tatt FK. Never seen any Reliant ink before.
Welcome to MMMotors Sir.

If it was registered before the MSVA procedure came in, your trike ought to be listed as Reliant motor tricycle, with no body type.
If it's been through the MSVA test it definitely won't say Rialto or whatever, as it's treated as a brand new vehicle.
There's still a lot of guys running around on iffy logbooks, with the original Reliant chassis number stamped onto a new trike frame. Still quite a few riding trikes that haven't got a single Reliant part on them, listed as Reliant on the papers too, simply cos the Reliant logbook already says motor tricycle on it. Obviously that's completely illegal & will eventually lead to the MOT tester refusing to test it. You may get away with it for a few years if you have a friendly local tester, but he's then obligated to notify DVLA & you'll receive a letter from them telling you to bring it into their workshops for inspection. If it ain't what it says on the
tin, paperwork, you'll have to MSVA it.
So, personally, I'd re-register it anyway. Not nearly as tough to do as some would have you believe & it'll be properly registered, so worth it for the peace of mind.
Let's see some piccies then.